Digital power supply and voltage sampling failure detection circuit thereof

Abstract

The utility model provides a detection circuit for voltage sampling failure of a digital power supply, which belongs to the field of electronic equipment for measurement and test and comprises a capacitor C1, a switching tube Q1, a switching tube Q2, a filter circuit, a sampling circuit, a main control chip and a pulse width modulation (PWM) driving circuit, the capacitor C1 is connected in parallel with the output end of the digital power supply, and the source electrode of the switching tube Q1 is connected with the positive electrode of the digital power supply. The drain electrode of the switch tube Q1 is respectively connected to the source electrode of the switch tube Q2 and the first input end of the sampling circuit, the drain electrode of the switch tube Q2 is respectively connected to the negative electrode of the digital power supply and the second input end of the sampling circuit, the filter circuit is connected in series between the drain electrode of the switch tube Q1 and the drain electrode of the switch tube Q2, and the output end of the sampling circuit is connected to the input end of the main control chip. The PWM signal output end of the main control chip is connected to the PWM driving circuit, and the PWM driving circuit outputs two PWM driving signals to respectively control the on or off of the switching tubes Q1 and Q2; the utility model also provides a digital power supply which is simple in circuit structure, does not need additional devices, and greatly reduces the cost.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic equipment for measuring and testing, in particular to a digital power supply and a detection circuit for voltage sampling failure thereof. Background Art

[0002] Most digital power supplies have constant voltage output, and most of them use voltage closed-loop control. In digital power supplies based on voltage closed-loop control, the output voltage is the controlled object of the closed-loop control, so it is inevitable to sample the output voltage of the power supply.

[0003] At present, whether the output voltage is sampled based on a pure analog circuit or a combination of an analog circuit and a digital circuit, it is inevitable that there will be sampling failures such as poor contact of the sampling terminal, loose crimping of the sampling line, aging of the sampling line, and aging and failure of electronic components in the sampling branch, which will eventually lead to failure of output voltage sampling. In closed-loop control, once the sampling fails, the AD unit of the main control chip will not be able to collect the output voltage value. As a result of closed-loop control, the duty cycle of the switching tube of the core device of the power supply will continue to increase until the maximum duty cycle is output, and then the highest voltage that the power supply hardware can support is output, which is very likely to cause overvoltage damage to the user's equipment.

[0004] In the prior art, the Chinese invention patent application "Digital power supply and its fault detection circuit, method and computer-readable storage medium" with publication number CN113161989A realizes that in the normal operation of the digital power supply, the reference conversion reference value generated by the reference voltage of the control circuit is detected, and when the difference between the reference conversion reference value and the preset standard conversion reference value is greater than the first preset threshold, the controller is controlled to stop driving the voltage converter, so as to avoid the controller from driving the voltage converter incorrectly due to the failure of the working power supply, thereby avoiding overvoltage damage to the electrical equipment. However, the detection circuit needs to set up a large number of circuits such as voltage stabilization circuit, analog-to-digital conversion circuit, calculation circuit, judgment circuit, etc., and many devices are used, resulting in a high cost of the detection circuit. Utility Model Content

[0005] The technical problem to be solved by the utility model is how to design a detection circuit for digital power supply voltage sampling failure with a simple structure and low cost.

[0006] The utility model solves the above technical problems through the following technical solutions: a detection circuit for failure of digital power supply voltage sampling, comprising: a capacitor C1, a switch tube Q1, a switch tube Q2, a filtering circuit, a sampling circuit, a main control chip MCU and a PWM drive circuit, the capacitor C1 is connected in parallel to the output end of the digital power supply, the source of the switch tube Q1 is connected to the positive electrode of the digital power supply, the drain of the switch tube Q1 is respectively connected to the source of the switch tube Q2 and the first input end of the sampling circuit, the drain of the switch tube Q2 is respectively connected to the negative electrode of the digital power supply and the second input end of the sampling circuit, the filtering circuit is connected in series between the drain of the switch tube Q1 and the drain of the switch tube Q2, the output end of the sampling circuit is connected to the input end of the main control chip MCU, the PWM signal output end of the main control chip MCU is connected to the PWM drive circuit, and the PWM drive circuit outputs two PWM drive signals to respectively control the switching tube Q1 and the switching tube Q2 to be turned on or off.

[0007] Preferably, the sampling circuit includes an operational amplifier, a resistor R1, a resistor R2, a resistor R3, a resistor R4, and a resistor R5. One end of the resistor R1 is connected to the drain of the switch tube Q1 as the first input end of the sampling circuit, and the other end is respectively connected to the positive input end of the operational amplifier and one end of the resistor R3. The other end of the resistor R3 is respectively connected to the output end of the operational amplifier and one end of the resistor R5. The other end of the resistor R5 is connected to the input end of the main control chip MCU. One end of the resistor R2 is connected to the drain of the switch tube Q2 as the second input end of the sampling circuit, and the other end is respectively connected to the reverse input end of the operational amplifier and one end of the resistor R4. The other end of the resistor R4 is grounded.

[0008] Preferably, the PWM drive circuit includes an isolated power supply E1, a drive chip U1, an isolated power supply E2 and a drive chip U2, the two PWM signal output ends of the main control chip MCU are respectively connected to the drive signal input ends of the drive chip U1 and the drive chip U2, the drive signal output end of the drive chip U1 is connected to the gate of the switch tube Q1, and the drive signal output end of the drive chip U2 is connected to the gate of the switch tube Q2, the isolated power supply E1 is connected between the main control chip MCU and the drive chip U1 for isolating the power supply to power the drive chip U1, and the isolated power supply E2 is connected between the main control chip MCU and the drive chip U2 for isolating the power supply to power the drive chip U2.

[0009] Preferably, the filtering circuit includes an inductor L1 and a capacitor C2, one end of the inductor L1 is respectively connected to the drain of the switch tube Q1 and the source of the switch tube Q2, and the other end is respectively connected to the upper plate of the capacitor C2 and one end of the resistor R1, and the lower plate of the capacitor C2 is respectively connected to the drain of the switch tube Q2 and one end of the resistor R2.

[0010] Preferably, the switch tube Q1 and the switch tube Q2 are IGBT or MOSFET tubes, and the model of the MOSFET tube is C3M0040120K.

[0011] Preferably, the signal of the main control chip MCU is TMS320F28377, the models of the isolated power supply E1 and the isolated power supply E2 are both QA121C3, and the models of the driver chip U1 and the driver chip U2 are both NSI6601.

[0012] Preferably, the model of the operational amplifier is AD8672.

[0013] The utility model also provides a digital power supply, comprising the detection circuit for digital power supply voltage sampling failure.

[0014] The advantages provided by the utility model are:

[0015] The utility model utilizes the sampling circuit at the output end of the digital power supply and the main control chip MCU to realize the detection of output voltage sampling failure, without the need to separately set peripheral circuits such as voltage stabilization circuit, analog-to-digital conversion circuit, calculation circuit, judgment circuit, etc. The circuit structure is simple, no additional devices are required, and the cost is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A topological diagram of a detection circuit for digital power supply voltage sampling failure provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the utility model more clear, the technical solution of the utility model is clearly and completely described below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, but not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0018] like Figure 1As shown, this embodiment provides a detection circuit for digital power supply voltage sampling failure, including capacitor C1, capacitor C2, inductor L1, switch tube Q1, switch tube Q2, operational amplifier, resistors R1-R5, main control chip MCU, isolated power supply E1, driver chip U1, isolated power supply E2 and driver chip U2, capacitor C1 is connected in parallel to the output end of the digital power supply, the source of the switch tube Q1 is connected to the positive electrode of the digital power supply, the drain of the switch tube Q1 is respectively connected to the source of the switch tube Q2 and one end of the inductor L1, the other end of the inductor L1 is respectively connected to the upper plate of the capacitor C2 and one end of the resistor R1, the drain of the switch tube Q2 is respectively connected to the negative electrode of the digital power supply, the lower plate of the capacitor C2 and one end of the resistor R2, the other end of the resistor R1 is respectively connected to the positive input end of the operational amplifier and one end of the resistor R3, the resistor The other end of R3 is respectively connected to the output end of the operational amplifier and one end of the resistor R5, the other end of the resistor R5 is connected to the input end of the main control chip MCU, the other end of the resistor R2 is respectively connected to the reverse input end of the operational amplifier and one end of the resistor R4, the other end of the resistor R4 is grounded, the two PWM signal output ends of the main control chip MCU are respectively connected to the drive signal input ends of the driver chip U1 and the driver chip U2, the drive signal output end of the driver chip U1 is connected to the gate of the switch tube Q1, and the drive signal output end of the driver chip U2 is connected to the gate of the switch tube Q2, the isolation power supply E1 is connected between the main control chip MCU and the driver chip U1 for isolating the power supply to power the driver chip U1, and the isolation power supply E2 is connected between the main control chip MCU and the driver chip U2 for isolating the power supply to power the driver chip U2.

[0019] Inductor L1 and capacitor C2 form a filter circuit.

[0020] The operational amplifier and resistors R1, R2, R3, R4, and R5 together constitute the sampling circuit of the output voltage. The operational amplifier is used to perform method and conditioning on the collected signal. Resistors R1, R2, R3, R4, and R5 are sampling resistors, which mainly play the role of voltage division. The main control chip MCU performs AD conversion (analog-to-digital conversion) on the output voltage and generates a PWM signal (switching tube drive pulse width modulation signal), while performing loop control and logic judgment. The main control chip MCU contains an AD unit, which performs analog-to-digital conversion on the sampling signal of the sampling circuit. The digital signal converted by the main control chip MCU performs zero point calibration and proportional operation to obtain the actual output voltage value U O .

[0021] The isolated power supply E1, the driver chip U1, the isolated power supply E2 and the driver chip U2 together constitute a PWM drive circuit, which is used to amplify the power and isolate the signal of the PWM signal generated by the main control chip MCU to drive the switch tube to turn on and off.

[0022] The switch tubes Q1 and Q2 are IGBT or MOSFET tubes. When MOSFET tubes are selected, the model is C3M0040120K. The signal of the main control chip MCU is TMS320F28377, the model of the isolated power supply E1 and the isolated power supply E2 are both QA121C3, the model of the driver chip U1 and the driver chip U2 are both NSI6601. The model of the operational amplifier is AD8672.

[0023] The utility model can detect the failure of output voltage sampling by using the sampling circuit of the digital power supply output end and the main control chip MCU, without the need to separately set peripheral circuits such as voltage stabilization circuit, analog-to-digital conversion circuit, calculation circuit, and judgment circuit. The circuit structure is simple, no additional devices are required, and the cost is greatly reduced. The detection circuit of the utility model is also suitable for a constant current source with closed-loop current control.

[0024] The utility model also provides a digital power supply, comprising the detection circuit for digital power supply voltage sampling failure.

[0025] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A detection circuit for digital power supply voltage sampling failure, characterized in that: include: Capacitor C1, switch tube Q1, switch tube Q2, filter circuit, sampling circuit, main control chip MCU and PWM drive circuit, capacitor C1 is connected in parallel to the output end of the digital power supply, the source of the switch tube Q1 is connected to the positive electrode of the digital power supply, the drain of the switch tube Q1 is respectively connected to the source of the switch tube Q2 and the first input end of the sampling circuit, the drain of the switch tube Q2 is respectively connected to the negative electrode of the digital power supply and the second input end of the sampling circuit, the filter circuit is connected in series between the drain of the switch tube Q1 and the drain of the switch tube Q2, the output end of the sampling circuit is connected to the input end of the main control chip MCU, the PWM signal output end of the main control chip MCU is connected to the PWM drive circuit, and the PWM drive circuit outputs two PWM drive signals to respectively control the switching on or off of the switch tube Q1 and the switch tube Q2.

2. The digital power supply voltage sampling failure detection circuit according to claim 1, characterized in that: The sampling circuit includes an operational amplifier, a resistor R1, a resistor R2, a resistor R3, a resistor R4, and a resistor R5. One end of the resistor R1 is connected to the drain of the switch tube Q1 as the first input end of the sampling circuit, and the other end is respectively connected to the positive input end of the operational amplifier and one end of the resistor R3. The other end of the resistor R3 is respectively connected to the output end of the operational amplifier and one end of the resistor R5. The other end of the resistor R5 is connected to the input end of the main control chip MCU. One end of the resistor R2 is connected to the drain of the switch tube Q2 as the second input end of the sampling circuit, and the other end is respectively connected to the reverse input end of the operational amplifier and one end of the resistor R4. The other end of the resistor R4 is grounded.

3. The digital power supply voltage sampling failure detection circuit according to claim 1, characterized in that: The PWM driving circuit includes an isolated power supply E1, a driving chip U1, an isolated power supply E2 and a driving chip U2. The two PWM signal output ends of the main control chip MCU are respectively connected to the driving signal input ends of the driving chip U1 and the driving chip U2. The driving signal output end of the driving chip U1 is connected to the gate of the switching tube Q1, and the driving signal output end of the driving chip U2 is connected to the gate of the switching tube Q2. The isolated power supply E1 is connected between the main control chip MCU and the driving chip U1 to isolate the power supply to power the driving chip U1, and the isolated power supply E2 is connected between the main control chip MCU and the driving chip U2 to isolate the power supply to power the driving chip U2.

4. The digital power supply voltage sampling failure detection circuit according to claim 2, characterized in that: The filter circuit includes an inductor L1 and a capacitor C2, one end of the inductor L1 is respectively connected to the drain of the switch tube Q1 and the source of the switch tube Q2, and the other end is respectively connected to the upper plate of the capacitor C2 and one end of the resistor R1, and the lower plate of the capacitor C2 is respectively connected to the drain of the switch tube Q2 and one end of the resistor R2.

5. The digital power supply voltage sampling failure detection circuit according to claim 1, characterized in that: The switch tube Q1 and the switch tube Q2 are IGBT or MOSFET tubes, and the model of the MOSFET tube is C3M0040120K.

6. The digital power supply voltage sampling failure detection circuit according to claim 1, characterized in that: The signal of the main control chip MCU is TMS320F28377, the models of the isolated power supply E1 and the isolated power supply E2 are both QA121C3, and the models of the driver chip U1 and the driver chip U2 are both NSI6601.

7. The digital power supply voltage sampling failure detection circuit according to claim 2, characterized in that: The model of the operational amplifier is AD8672.

8. A digital power supply, characterized in that: A detection circuit for digital power supply voltage sampling failure comprising the circuit described in any one of claims 1 to 7.

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