Direct-current test power supply with characteristic self-checking and double-feedback control functions

Abstract

The invention provides a direct-current test power supply with characteristic self-checking and double-feedback control functions. The direct-current test power supply comprises an alternating-current voltage regulator, a rectifying and filtering circuit, a power adjusting circuit, an adjustable load, a feedback circuit and a controller. After the output voltage of an external alternating current power supply is regulated by the alternating current voltage regulator, smooth direct current obtained by the rectification filter circuit is sent to the power regulation circuit to output constant-voltage direct current to supply power to an adjustable load; at the moment, the controller dynamically adjusts the size of the adjustable load, generates a PWM (Pulse Width Modulation) signal, provides the PWM signal to the power adjusting circuit, and further obtains the voltage and current of the direct current which are correspondingly output by the power adjusting circuit after the power adjusting circuit is adjusted based on the alternating current voltage regulator or / and the adjustable load every time, and carrying out self-inspection of a specific index and dynamic adjustment of the duty ratio of the PWM signal. According to the invention, when a power supply is provided for direct current equipment, whether technical indexes such as voltage stabilization, current stabilization and ripple of the device meet technical requirements or not can be detected through characteristic self-inspection.

Description

Technical Field

[0001] The invention relates to the technical field of electric power supply, and in particular to a direct current test power supply with characteristic self-checking and dual feedback control functions. Background Art

[0002] The DC system is an important part of the substation. It provides a stable and reliable working environment for the substation secondary circuit equipment (such as relay protection, automatic devices, etc.), and is one of the fundamental guarantees for the stable operation of the substation. In order to protect the reliability of the DC system, before connecting new equipment to the DC system, an external DC test power supply is usually used to debug the new equipment, and the new equipment can only be connected to the DC system for operation after confirming that the new equipment is fully functional, safe and reliable.

[0003] With the rapid development of my country's power industry, higher requirements are put forward for the stability and reliability of DC test power supply. However, the existing test power supply has the problems of poor voltage and current stability and no performance self-test function.

[0004] Therefore, in order to make up for the shortcomings of existing test power supplies on the market, it is necessary to design a portable, practical, reliable DC test power supply with characteristic self-test function and high stability. While providing power to DC equipment, it can also use characteristic self-test to detect whether its own technical indicators such as voltage regulation, current regulation, ripple, etc. meet the technical requirements. Summary of the invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a DC test power supply with characteristic self-test and dual feedback control functions, which can provide power to DC equipment and can also detect whether its own technical indicators such as voltage regulation, current regulation, ripple, etc. meet the technical requirements through characteristic self-test.

[0006] In order to solve the above technical problems, an embodiment of the present invention provides a DC test power supply with characteristic self-test and dual feedback control functions, including an AC voltage regulator, a rectifier filter circuit, a power adjustment circuit, an adjustable load, a feedback circuit and a controller; wherein,

[0007] The voltage input end of the AC voltage regulator is connected to an external AC power supply, and the voltage output end is connected in series with the rectifier filter circuit and the power adjustment circuit in sequence and then connected to the adjustable load to form a power supply circuit for supplying power to the adjustable load;

[0008] The first end of the controller is connected to the control end of the power adjustment circuit, the second end is connected between the power adjustment circuit and the adjustable load through the feedback circuit, and the third end is connected to the control end of the adjustable load;

[0009] The AC voltage regulator is provided with a plurality of optional voltage ranges, which are used to adjust the output voltage of the external AC power supply once or multiple times based on one or more voltage ranges selected by the user;

[0010] The rectification and filtering circuit is used to perform full-wave rectification and filtering on the AC voltage regulated by the AC voltage regulator to obtain smooth DC power;

[0011] The power adjustment circuit is used to perform sustainable power adjustment based on the PWM signal with a certain duty cycle output by the controller, so as to convert the direct current output by the rectifier and filter circuit into direct current with a constant voltage and supply power to the adjustable load;

[0012] The feedback circuit is used to sample the voltage and current of the direct current output by the power adjustment circuit;

[0013] The controller is used to adjust the size of the adjustable load once or multiple times based on user instructions; and to generate a PWM signal and provide it to the power adjustment circuit, and further obtain the voltage and current of the output DC power corresponding to each adjustment of the power adjustment circuit based on the AC voltage regulator and / or the adjustable load collected by the feedback circuit, and perform self-inspection of specific indicators and dynamic adjustment of the duty cycle of the PWM signal; wherein the specific indicators include voltage regulation accuracy, current regulation accuracy and ripple factor.

[0014] The controller includes an adjustable load control module, a PWM signal generation module, a characteristic self-checking module and a PWM signal adjustment module;

[0015] The adjustable load control module is used to adjust the size of the adjustable load once or multiple times based on user instructions;

[0016] The PWM signal generating module is used to generate a PWM signal and provide it to the power adjustment circuit;

[0017] The characteristic self-test module is used to calculate the voltage stabilization accuracy, current stabilization accuracy and ripple factor of the AC voltage regulator and / or the adjustable load after each adjustment based on the voltage and current of the DC power output by the power adjustment circuit after each adjustment based on the AC voltage regulator and / or the adjustable load collected by the feedback circuit;

[0018] The PWM signal adjustment module is used to compare the voltage and current of the DC power output corresponding to each adjustment of the power adjustment circuit based on the AC voltage regulator and / or the adjustable load collected by the feedback circuit with the preset voltage threshold and current threshold respectively, and dynamically adjust the duty cycle of the PWM signal according to the comparison result, and further provide the dynamically adjusted PWM signal to the power adjustment circuit.

[0019] Among them, through the formula The voltage stabilization accuracy δ is calculated as U ; Through the formula The steady flow accuracy δ is calculated as I ; Through the formula R = V ripple / V dc , calculate and obtain the ripple coefficient R;

[0020] Among them, U M is the fluctuation limit of the output voltage; U Z is the measured value of the output voltage; I M is the fluctuation limit of the output current; I Z is the measured value of the output current; V ripple is the ripple voltage in the output voltage; V dc is the DC average value of the output voltage.

[0021] Among them, it also includes: an AC input circuit; wherein,

[0022] The AC input circuit is arranged between the external AC power source and the AC voltage regulator, and is used for electrically isolating the output voltage of the external AC power source and then inputting it.

[0023] Implementing the embodiments of the present invention has the following beneficial effects:

[0024] When the DC test power supply in the present invention is connected to an external AC power supply, a power supply circuit formed by an AC voltage regulator, a rectifier and a filter circuit and a power adjustment circuit outputs a constant voltage DC power to supply power to an adjustable load. At the same time, when the AC voltage regulator adjusts the voltage through an optional voltage range and / or the adjustable load adjusts the size through a controller, the controller performs a self-check of specific indicators according to the voltage and current of the output DC power corresponding to the power adjustment circuit, thereby achieving the purpose of providing power to the DC device and detecting whether its own technical indicators such as voltage stability, current stability, ripple, etc. meet the technical requirements through characteristic self-checking. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0026] Figure 1 A logical structure connection diagram of a DC test power supply with characteristic self-checking and dual feedback control functions provided by an embodiment of the present invention;

[0027] Figure 2 Another logical structure connection diagram of a DC test power supply with characteristic self-checking and dual feedback control functions provided by an embodiment of the present invention;

[0028] Figure 3 for Figure 1 and 2 Functional structure diagram of the controller in the figure;

[0029] Figure 4 for Figure 1 and 2 The circuit connection diagram of the rectifier and filter circuit in the figure;

[0030] Figure 5 for Figure 1 and 2 Circuit connection diagram of medium power regulation circuit;

[0031] Figure 6 for Figure 1 and 2 Circuit connection diagram of medium power feedback circuit. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] like Figures 1 to 6 As shown in the figure, a DC test power supply with characteristic self-checking and dual feedback control functions is proposed in an embodiment of the present invention, including an AC voltage regulator 2, a rectifier filter circuit 3, a power adjustment circuit 4, an adjustable load 5, a feedback circuit 6 and a controller 7; wherein,

[0034] The voltage input end of the AC voltage regulator 2 is connected to an external AC power source AC (such as 220V AC), and the voltage output end is connected in series with a rectifier filter circuit 3 and a power adjustment circuit 4 in sequence and then connected to an adjustable load 5 to form a power supply circuit for supplying power to the adjustable load 5; it can be understood that an AC input circuit 1 (such as Figure 2As shown) to electrically isolate the AC output voltage of the external AC power supply and then input it; it should be noted that the adjustable load 5 is an adjustable power resistor;

[0035] The first end of the controller 7 is connected to the control end of the power adjustment circuit 4, the second end is connected between the power adjustment circuit 4 and the adjustable load 5 through the feedback circuit 6, and the third end is connected to the control end of the adjustable load 5; it can be understood that the AC voltage regulator 2, the rectifier and filter circuit 3, the power adjustment circuit 4, and the adjustable load 5 in the power supply circuit are all realized through strong electric signals to input and output voltage, and the controller 7 and the control end of the power adjustment circuit 4, the feedback circuit 6, and the control end of the adjustable load 5 are all realized through weak electric signals to control signals and collect data;

[0036] The AC input circuit 1 is used to electrically isolate the output voltage of the external AC power supply and then input it;

[0037] The AC voltage regulator 2 is provided with a plurality of selectable voltage ranges (such as rotary buttons) for adjusting the output voltage of the external AC power source AC, either isolated or not, once or multiple times based on one or more voltage ranges selected by the user;

[0038] The rectifier and filter circuit 3 is used to perform full-wave rectification and filtering on the AC voltage regulated by the AC voltage regulator 2 to obtain smooth DC power;

[0039] The power adjustment circuit 4 is used to perform sustainable power adjustment based on the PWM signal with a certain duty cycle output by the controller 7, so as to convert the DC power output by the rectifier and filter circuit 3 into a DC power with a constant voltage and supply power to the adjustable load 5;

[0040] The feedback circuit 6 is used to sample the voltage and current of the DC power output by the power adjustment circuit 4;

[0041] The controller 7 is used to adjust the size of the adjustable load 5 once or multiple times based on user instructions; and to generate a PWM signal and provide it to the power adjustment circuit 4, and further obtain the voltage and current of the output DC power corresponding to each adjustment of the power adjustment circuit 4 based on the AC voltage regulator 2 and / or the adjustable load 5 collected by the feedback circuit 6, and perform self-inspection of specific indicators and dynamic adjustment of the duty cycle of the PWM signal; wherein the specific indicators include voltage regulation accuracy, current regulation accuracy and ripple factor.

[0042] In the embodiment of the present invention, the controller 7 includes an adjustable load control module 71, a PWM signal generating module 72, a characteristic self-checking module 73 and a PWM signal adjusting module 74 (such as Figure 3 shown); among which,

[0043] The adjustable load control module 71 is used to adjust the size of the adjustable load 5 once or multiple times based on user instructions;

[0044] A PWM signal generating module 72, used for generating a PWM signal and providing it to the power regulating circuit 4;

[0045] The characteristic self-checking module 73 is used to calculate the voltage stabilization accuracy, current stabilization accuracy and ripple factor of the corresponding AC voltage regulator 2 or / and the adjustable load 5 after each adjustment according to the voltage and current of the DC power output by the power adjustment circuit 4 after each adjustment based on the AC voltage regulator 2 or / and the adjustable load 5 collected by the feedback circuit 6; wherein, through the formula Calculate the voltage regulation accuracy δ U ; Through the formula The calculated steady flow accuracy δ I ; Through the formula R = V ripple / V dc , calculate the ripple coefficient R; U M is the fluctuation limit of the output voltage; U Z is the measured value of the output voltage; I M is the fluctuation limit of the output current; I Z is the measured value of the output current; V ripple is the ripple voltage in the output voltage; V dc is the DC average value of the output voltage;

[0046] The PWM signal adjustment module 74 is used to compare the voltage and current of the DC output corresponding to each adjustment of the power adjustment circuit 4 based on the AC voltage regulator 2 and / or the adjustable load 5 collected by the feedback circuit 6 with the preset voltage threshold and current threshold respectively, and dynamically adjust the duty cycle of the PWM signal according to the comparison result, and further provide the dynamically adjusted PWM signal to the power adjustment circuit.

[0047] It should be noted that voltage regulation accuracy refers to the relative change in the output voltage, usually expressed as a percentage, and the smaller the value, the better the voltage regulation performance. Similarly, current regulation accuracy refers to the relative change in the output current, usually expressed as a percentage, and the smaller the value, the better the current regulation performance. The fluctuation limit values ​​of the output voltage and output current refer to the voltage and current before each adjustment of the AC voltage regulator 2 and the adjustable load 5. Ripple voltage refers to the AC component in the DC voltage, which is mainly obtained after rectification and filtering of the AC voltage. Since there are residual AC components due to unclean filtering, even if it is powered by a battery, ripples will be generated due to load fluctuations. It is obtained by measuring the output DC power of the power adjustment circuit 4 before each adjustment of the adjustable load 5.

[0048] In the embodiment of the present invention, the rectifier filter circuit 3 is composed of rectifier diodes D1, D2, D3, and D4 to form a full-wave rectifier circuit, and in order to make the waveform of the direct current smoother and more stable, a filter circuit composed of capacitors C1, C2, C3, and C4 is used to achieve (such as Figure 4 ). Among them,

[0049] In the full-wave rectifier circuit composed of rectifier diodes D1, D2, D3, and D4, when the AC voltage changes to the positive half cycle, there are two paths for the voltage to flow, namely V1-D1-V2-ground and ground-V2-D4-V1. The ground is used as the zero point reference point. The positive and negative DC voltages are obtained by rectifying the positive and negative half cycles of the AC voltage. The relationship between the rectified voltage and the power supply voltage is V2 = 0.9V1. Among them, V1 is the output voltage of the upper outlet of the transformer; V2 is the output voltage of the lower outlet of the transformer.

[0050] In the filter circuit composed of capacitors C1, C2, C3, and C4, capacitors C1 and C2 are filter electrolytic capacitors. When the AC potential is in the positive half cycle, C1 is charged through D1 and D4, and when it is in the negative half cycle, C2 is charged through D2 and D3. The charging time constant is τ1 = R1*C. Among them, R1 is the DC resistance of the transformer secondary winding and the forward resistance of the rectifier diode. The resistance is small, and the capacitor is quickly charged to the maximum AC voltage.

[0051] When there is no load, the output voltage is 1.414V1. When there is a load, the discharge time constant τ2=RL*C, RL is the load, and a smooth load voltage is obtained. C3 and C4 are filter capacitors, which mainly eliminate high-frequency interference and provide a way for high-frequency signals to flow to the ground.

[0052] In the embodiment of the present invention, the power adjustment circuit 4 (such as Figure 5 The PWM signal is provided by the controller 7, and the common emitter amplifier circuit formed by Q1 performs signal amplification processing. The PWM signal makes Q2 work in the switching state to ensure the adjustable output voltage and current. When Q2 is turned on, the circuit outputs normally and charges C2. When Q2 is turned off, C2 discharges to ensure continuous output to the load. However, in order to prevent the impact caused by the sudden change of current when C2 is discharged, the series inductor L1 with the opposite effect is added to eliminate the current impact. In addition, in order to prevent the impact caused by the sudden change of voltage at the moment of Q2 turning on, the circuit works normally.

[0053] In an embodiment of the present invention, the feedback circuit (such as Figure 6 The comparator circuit is composed of two high-precision and low-drift integrated operational amplifiers, which use the high-gain transmission characteristics to achieve the function of current and voltage stabilization. Figure 6It can be seen that current sampling and voltage sampling are performed at the voltage and current output ports respectively, and the sampled signals are amplified and compared with the set current and voltage references. Only when the voltage or current values ​​of the positive and negative input ports of the operational amplifier are equal and the voltage difference or current difference is 0, the output signal of the comparator is 0, and no algorithm adjustment compensation is required; if the voltage or current values ​​of the positive and negative input ports of the operational amplifier are not equal and the voltage difference or current difference is not 0, the output signal of the comparator is not 0, and the control center will make corresponding numerical adjustments according to the size of the output signal to make the actual output voltage and current values ​​consistent with the set values.

[0054] The implementation of the embodiments of the present invention has the following beneficial effects:

[0055] When the DC test power supply in the present invention is connected to an external AC power supply, a power supply circuit formed by an AC voltage regulator, a rectifier and a filter circuit and a power adjustment circuit outputs a constant voltage DC power to supply power to an adjustable load. At the same time, when the AC voltage regulator adjusts the voltage through an optional voltage range and / or the adjustable load adjusts the size through a controller, the controller performs a self-check of specific indicators according to the voltage and current of the output DC power corresponding to the power adjustment circuit, thereby achieving the purpose of providing power to the DC device and detecting whether its own technical indicators such as voltage stability, current stability, ripple, etc. meet the technical requirements through characteristic self-checking.

[0056] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A DC test power supply with characteristic self-checking and dual feedback control functions, characterized in that: It includes an AC voltage regulator, a rectifier filter circuit, a power adjustment circuit, an adjustable load, a feedback circuit and a controller; wherein, The voltage input end of the AC voltage regulator is connected to an external AC power supply, and the voltage output end is connected in series with the rectifier filter circuit and the power adjustment circuit in sequence and then connected to the adjustable load to form a power supply circuit for supplying power to the adjustable load; The first end of the controller is connected to the control end of the power adjustment circuit, the second end is connected between the power adjustment circuit and the adjustable load through the feedback circuit, and the third end is connected to the control end of the adjustable load; The AC voltage regulator is provided with a plurality of optional voltage ranges, which are used to adjust the output voltage of the external AC power supply once or multiple times based on one or more voltage ranges selected by the user; The rectification and filtering circuit is used to perform full-wave rectification and filtering on the AC voltage regulated by the AC voltage regulator to obtain smooth DC power; The power adjustment circuit is used to perform sustainable power adjustment based on the PWM signal with a certain duty cycle output by the controller, so as to convert the direct current output by the rectifier and filter circuit into direct current with a constant voltage and supply power to the adjustable load; The feedback circuit is used to sample the voltage and current of the direct current output by the power adjustment circuit; The controller is used to adjust the size of the adjustable load once or multiple times based on user instructions; and to generate a PWM signal and provide it to the power adjustment circuit, and further obtain the voltage and current of the output DC power corresponding to each adjustment of the power adjustment circuit based on the AC voltage regulator and / or the adjustable load collected by the feedback circuit, and perform self-inspection of specific indicators and dynamic adjustment of the duty cycle of the PWM signal; wherein the specific indicators include voltage regulation accuracy, current regulation accuracy and ripple factor.

2. The DC test power supply with characteristic self-checking and dual feedback control functions as claimed in claim 1, characterized in that: The controller includes an adjustable load control module, a PWM signal generation module, a characteristic self-checking module and a PWM signal adjustment module; wherein, The adjustable load control module is used to adjust the size of the adjustable load once or multiple times based on user instructions; The PWM signal generating module is used to generate a PWM signal and provide it to the power adjustment circuit; The characteristic self-test module is used to calculate the voltage stabilization accuracy, current stabilization accuracy and ripple factor of the AC voltage regulator and / or the adjustable load after each adjustment based on the voltage and current of the DC power output by the power adjustment circuit after each adjustment based on the AC voltage regulator and / or the adjustable load collected by the feedback circuit; The PWM signal adjustment module is used to compare the voltage and current of the DC power output corresponding to each adjustment of the power adjustment circuit based on the AC voltage regulator and / or the adjustable load collected by the feedback circuit with the preset voltage threshold and current threshold respectively, and dynamically adjust the duty cycle of the PWM signal according to the comparison result, and further provide the dynamically adjusted PWM signal to the power adjustment circuit.

3. The DC test power supply with characteristic self-checking and dual feedback control functions as claimed in claim 2, characterized in that: By formula The voltage stabilization accuracy δ is calculated as U ; Through the formula The steady flow accuracy δ is calculated as I ; Through the formula R = V ripple / V dc , calculate and obtain the ripple coefficient R; Among them, U M is the fluctuation limit of the output voltage; U Z is the measured value of the output voltage; I M is the fluctuation limit of the output current; I Z is the measured value of the output current; V ripple is the ripple voltage in the output voltage; V dc is the DC average value of the output voltage.

4. The DC test power supply with characteristic self-checking and dual feedback control functions as claimed in claim 3, characterized in that: Also includes: AC input circuit; where: The AC input circuit is arranged between the external AC power source and the AC voltage regulator, and is used for electrically isolating the output voltage of the external AC power source and then inputting it.

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