CN108241129B - Device and method for monitoring output filter capacitor of switching power supply - Google Patents

Abstract

The switching power supply output filter capacitor device and method of the present invention, wherein the switching power supply output filter capacitor device may include a trigger circuit, a voltage measurement circuit and a processing module; the input end of the trigger circuit is connected to the control signal end of the switching power supply module to be tested, and the output end The signal input end of the voltage measurement circuit is connected; the measurement input end of the voltage measurement circuit is connected to the output end of the filter capacitor of the switching power supply module to be tested, and the measurement output end is connected to the processing module. Therefore, when the trigger circuit receives the first transition edge signal and the second transition edge signal, the first trigger signal and the second trigger signal are generated; when the voltage measurement circuit receives the first trigger signal and the second trigger signal, the The output voltage of the filter capacitor is sampled and measured, respectively, to obtain the first output voltage signal and the second output voltage signal; and through the processing of the processing module, the capacity and ESR of the filter capacitor can be obtained. This greatly simplifies the monitoring circuit and reduces the monitoring cost.

Description

Switching power supply output filter capacitor monitoring device and method

technical field

The invention relates to the technical field of switching power supply monitoring, in particular to a device and method for monitoring the output filter capacitance of a switching power supply.

Background technique

With the development of switching power supply technology, it has been widely used in household appliances, instrumentation, consumer electronics and other scenarios. Since the power module is the basis of the entire circuit, its reliability is directly related to the normal operation of the entire circuit. For the switching power supply module, the filter capacitor for filtering is the part with the highest probability of failure in the entire module. More than 60% of the failures of switching power supply modules are caused by the failure of filter capacitors. After a long-term aging of the filter capacitor, the electrolyte will decrease, thereby causing the capacitance value of the filter capacitor to decrease and the Equivalent Series Resistance (ESR) to increase. Usually switching power supply output filter capacitance monitoring is by connecting a current sensor in series with the inductor, and connecting a voltage sensor in parallel at the output end to measure the current and output voltage flowing through the inductor, but two sensors are added, which increases the implementation cost of the hardware circuit. At the same time, since the current sensor needs to be connected to the circuit in series, the structure of the circuit will be changed, resulting in inconvenient monitoring and use.

At present, the traditional switching power supply output filter capacitor monitoring can sample the output voltage signal at a specific node, and obtain the output filter capacitor capacity and ESR through calculation. However, during the implementation process, the inventor found that there are at least the following problems in the traditional technology: the monitoring circuit for monitoring the output filter capacitor of the traditional switching power supply is complicated, which increases the monitoring cost.

SUMMARY OF THE INVENTION

Based on this, it is necessary to provide a switching power supply output filter capacitor device and method in view of the complex monitoring circuit of the switching power supply output filter capacitor monitoring in the traditional technical solution.

In order to achieve the above purpose, on the one hand, an embodiment of the present invention provides a switching power supply output filter capacitor device, including a trigger circuit, a voltage measurement circuit and a processing module; the input end of the trigger circuit is connected to the control signal end of the switching power supply module to be tested, The output terminal is connected to the signal input terminal of the voltage measurement circuit; the measurement input terminal of the voltage measurement circuit is connected to the output terminal of the filter capacitor of the switching power supply module to be tested, and the measurement output terminal is connected to the processing module;

The trigger circuit transmits the first trigger signal generated according to the first transition edge signal input by the switching power supply module to be tested to the voltage measurement circuit; when the voltage measurement circuit receives the first trigger signal, it samples the output voltage of the filter capacitor measuring, and transmitting the obtained first output voltage signal to the processing module;

The trigger circuit transmits the second trigger signal generated according to the second transition edge signal of the switching power supply module to be tested to the voltage measurement circuit; when the voltage measurement circuit receives the second trigger signal, the output voltage of the filter capacitor is sampled and measured , and transmit the obtained second output voltage signal to the processing module;

The processing module processes the first output voltage signal and the second output voltage signal to obtain the capacity and ESR of the filter capacitor.

In one of the embodiments, the first transition edge signal is a rising edge signal; the second transition edge signal is a falling edge signal.

In one of the embodiments, the trigger circuit includes a flip-flop, an XOR and a delay;

The first input end of the flip-flop is connected to the signal output end of the XOR, the first output end is connected to one end of the delayer, the second output end is connected to the second input end of the flip-flop; the first signal input end of the XOR is connected to The control signal end of the switching power supply module to be tested, the second signal input end is connected to the other end of the delayer; the signal output end of the XOR is connected to the signal input end of the voltage measurement circuit.

In one of the embodiments, the flip-flop is a D flip-flop, a JK flip-flop or an RS flip-flop.

In one of the embodiments, the voltage measurement circuit includes an acquisition module;

The control end of the acquisition module is connected to the signal output end of the trigger circuit, the input end is connected to the output end of the filter capacitor, and the output end is connected to the processing module.

In one of the embodiments, the voltage measurement circuit further includes an amplifier;

The input end of the amplifier is connected to the output end of the filter capacitor, and the output end is connected to the input end of the acquisition module.

In one of the embodiments, the amplifier is an isolated amplifying module or a non-isolated amplifying module.

In one embodiment, the isolation amplifier module is a transformer isolation amplifier module or an optocoupler isolation amplifier module.

On the other hand, an embodiment of the present invention also provides a method for monitoring the output filter capacitance of a switching power supply, including the following steps:

Receive the first output voltage signal and the second output voltage signal transmitted by the voltage measurement circuit; the first output voltage signal is the first trigger generated by the voltage measurement circuit after receiving the trigger circuit according to the first transition edge signal of the switching power supply module to be tested signal, the output voltage of the filter capacitor is sampled and measured; the second output voltage signal is obtained when the voltage measurement circuit receives the second trigger signal generated by the trigger circuit according to the second edge signal of the switching power supply module to be tested. , obtained by sampling and measuring the output voltage of the filter capacitor;

Process the first output voltage signal and the second output voltage signal to obtain the capacity and ESR of the filter capacitor.

In one of the embodiments, the first transition edge signal is a rising edge signal; the second transition edge signal is a falling edge signal.

A technical scheme in the above-mentioned technical scheme has the following advantages and beneficial effects:

The input end of the trigger circuit is connected to the control signal end of the switching power supply module to be tested, and the output end is connected to the signal input end of the voltage measurement circuit, so that the trigger circuit receives the first transition edge signal and the second jump signal of the switching power supply module to be tested. When the edge signal is changed, the first trigger signal and the second trigger signal generated respectively can be transmitted to the voltage measurement circuit; the measurement input end of the voltage measurement circuit is connected to the output end of the filter capacitor of the switching power supply module to be tested, so that the voltage measurement circuit When the first trigger signal and the second trigger signal can be received, the output voltage of the filter capacitor is sampled and measured, and the obtained first output voltage signal and second output voltage signal are transmitted to the processing module; through the measurement of the voltage measurement circuit The output end is connected to the processing module, so that the capacity and ESR of the filter capacitor can be obtained by processing the first output voltage signal and the second output voltage signal, which greatly simplifies the monitoring circuit for monitoring the output filter capacitor of the switching power supply module to be tested. Reduced monitoring costs.

Description of drawings

The above and other objects, features and advantages of the present invention will become more apparent from a more detailed description of the preferred embodiments of the invention shown in the accompanying drawings. The same reference numerals refer to the same parts throughout the drawings, and the drawings have not been intentionally drawn to scale, the emphasis being placed on illustrating the gist of the present invention.

Fig. 1 is a schematic diagram of the ESR processing flow of the filter capacitor in the traditional switching power supply;

2 is a schematic structural diagram of Embodiment 1 of the switching power supply output filter capacitor monitoring device according to the present invention;

3 is a schematic diagram of a specific structure of an embodiment of a switching power supply output filter capacitor monitoring device according to the present invention;

4 is a schematic structural diagram of a trigger circuit of an embodiment of a switching power supply output filter capacitor monitoring device according to the present invention;

5 is a schematic diagram of a specific structure of a trigger circuit of an embodiment of a switching power supply output filter capacitor monitoring device according to the present invention;

6 is a schematic structural diagram of a voltage measurement circuit according to an embodiment of a switching power supply output filter capacitance monitoring device according to the present invention;

7 is a schematic diagram of a specific structure of a voltage measurement circuit according to an embodiment of a switching power supply output filter capacitance monitoring device according to the present invention;

FIG. 8 is a schematic flowchart of Embodiment 1 of a method for monitoring the output filter capacitor of a switching power supply according to the present invention.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the related drawings. Preferred embodiments of the invention are shown in the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It should be noted that when an element is referred to as being "connected" to another element, it can be directly connected to and integrated with the other element, or intervening elements may also be present. The terms "installed," "one end," "the other end," and similar expressions used herein are for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

One of the application scenarios of the embodiments of the switching power supply output filter capacitor monitoring device and method of the present invention:

Figure 1 is a schematic diagram of the ESR processing flow of the filter capacitor in the traditional switching power supply. As shown in Figure 1, the traditional ESR monitoring of the filter capacitor in the switching power supply module to be tested is usually by connecting a current in series with the inductor in the switching power supply module to be tested. Sensor, a voltage sensor is connected in parallel at the output end of the switching power supply module to be tested to measure the inductor current flowing through the inductor and the output voltage at the output end of the switching power supply module to be tested. Since the ratio of the output ripple voltage to the inductor ripple current is the ESR evaluation value, so ESR is calculated from the inductor current and output ripple using empirical mode decomposition (EMD) and Hilbert transform (HHT).

Taking the Buck-type circuit as the switching power supply module to be tested as an example, the traditional ESR processing flow of the filter capacitor in the switching power supply is as follows: Saber simulation can be performed on the Buck-type circuit first, such as simulation circuit design, parameter setting and feature signal extraction; then The inductor current signal is measured by the current sensor, and the filter capacitor voltage information is measured by the voltage sensor. The IMFs (eigenmode function) are obtained by empirical mode decomposition of the current signal and the voltage signal; H(ω,t) (HHT transformation function) is obtained by performing HHT transformation on the IMFs, and α is obtained by H(ω,t) (t) (transient amplitude), which in turn gives the ESR. The traditional filter capacitor monitoring of the switching power supply module to be tested needs to measure two signals, the inductor current and the filter capacitor output ripple, so two sensors need to be added to the circuit, which increases the implementation cost of the hardware circuit, thereby increasing the complexity of the hardware circuit . At the same time, since the current sensor needs to be connected to the circuit in series, the structure of the circuit will be changed, which is not conducive to the application.

In the embodiment of the present invention, the first and second transition edge signals of the switching power supply module to be tested can be received by the trigger circuit, thereby generating the first trigger signal and the second trigger signal; the voltage measurement circuit can be used to receive When the first trigger signal and the second trigger signal are reached, the output voltage of the filter capacitor is sampled and measured to obtain the first output voltage signal and the second output voltage signal; the first output voltage signal and the second output voltage can be processed by the processing module. The capacity and ESR of the filter capacitor are obtained from the voltage signal, thereby greatly simplifying the monitoring circuit for monitoring the output filter capacitor of the switching power supply module to be tested, and reducing the monitoring cost.

In order to solve the problem that the monitoring circuit for monitoring the output filter capacitor of the switching power supply is complicated in the traditional technical solution, the present invention provides the first embodiment of an output filter capacitor device of the switching power supply. FIG. 2 is a schematic structural diagram of Embodiment 1 of the switching power supply output filter capacitor device according to the present invention. As shown in FIG. 2 , it may include a trigger circuit 210, a voltage measurement circuit 220 and a processing module 230; the input end of the trigger circuit 210 is connected to the switching power supply to be tested. The control signal terminal and the output terminal of the module are connected to the signal input terminal of the voltage measurement circuit 220 ; the measurement input terminal of the voltage measurement circuit 220 is connected to the output terminal of the filter capacitor of the switching power supply module to be tested, and the measurement output terminal is connected to the processing module 230 .

The trigger circuit 210 transmits the first trigger signal generated according to the first transition edge signal input by the switching power supply module to be tested to the voltage measurement circuit 220; when the voltage measurement circuit 220 receives the first trigger signal, the output of the filter capacitor is The voltage is sampled and measured, and the obtained first output voltage signal is transmitted to the processing module 230; the trigger circuit 210 transmits the second trigger signal generated according to the second transition edge signal of the switching power supply module to be tested to the voltage measurement circuit 220; When receiving the second trigger signal, the voltage measurement circuit 220 samples and measures the output voltage of the filter capacitor, and transmits the obtained second output voltage signal to the processing module 230; the processing module 230 processes the first output voltage signal and the second output voltage Voltage signal, get the capacity and ESR of the filter capacitor.

The trigger circuit 210 may refer to a circuit with a steady state, for example, when an appropriate pulse is applied to the trigger circuit, the desired transition output can be activated; the trigger circuit 210 may also refer to an unsteady circuit. The switching power supply module to be tested may include a control signal terminal, and the control signal terminal may be the control signal terminal of the switch tube of the switching power supply module to be tested. For example, the switch tube of the switching power supply module to be tested is MOS (Metal-Oxide-Semiconductor Field-Effect Transistor). , metal-oxide semiconductor field effect) tube, the control signal terminal is the gate terminal of the MOS tube. The switching power supply module to be tested may include a filter capacitor, and the output end of the filter capacitor may be connected to a load.

The control signal input to the control signal terminal of the switching power supply module to be tested may include a first transition edge signal and a second transition edge signal. For example, when the input control signal is a PWM (Pulse Width Modulation, pulse width modulation) control signal, the first The transition edge signal can be the transition edge signal when the PWM control signal changes from high level to low level, or the transition edge signal when the PWM control signal changes from low level to high level; the second transition edge The signal can be a transition edge signal when the PWM control signal changes from a high level to a low level, or can be a transition edge signal when the PWM control signal changes from a low level to a high level.

Preferably, when the first transition edge signal is the transition edge signal when the PWM control signal changes from high level to low level, the second transition edge signal is the transition edge signal when the PWM control signal changes from low level to high level Jumping edge signal; when the first jumping edge signal is the jumping edge signal when the PWM control signal changes from low level to high level, the second jumping edge signal is the PWM control signal changing from high level to low level. The usual transition edge signal.

Specifically, the input end of the trigger circuit 210 is connected to the control signal end of the switching power supply module to be tested, and the output end is connected to the signal input end of the voltage measurement circuit 220, so that the trigger circuit 210 receives the first jump of the switching power supply module to be tested. When the edge signal and the second transition edge signal are used, the respectively generated first trigger signal and second trigger signal can be transmitted to the voltage measurement circuit 220; the measurement input end of the voltage measurement circuit 220 is connected to the filter capacitor of the switching power supply module to be tested Therefore, when the voltage measurement circuit 220 receives the first trigger signal and the second trigger signal, it samples and measures the output voltage of the filter capacitor respectively, and transmits the obtained first output voltage signal and second output voltage signal to The processing module 230 is connected to the processing module 230 through the measurement output end of the voltage measurement circuit 220, so that the capacity and ESR of the filter capacitor can be obtained by processing the first output voltage signal and the second output voltage signal, thereby greatly simplifying the switch to be tested. A monitoring circuit for monitoring the output filter capacitor of the power module.

In the above embodiment of the switching power supply output filter capacitor monitoring device, the input end of the trigger circuit is connected to the control signal end of the switching power supply module to be tested, the output end is connected to the signal input end of the voltage measurement circuit; the measurement input end of the voltage measurement circuit is connected to the switch to be tested The output end of the filter capacitor of the power supply module and the measurement output end are connected to the processing module. Therefore, when the trigger circuit receives the first transition edge signal and the second transition edge signal of the switching power supply module to be tested, the first trigger signal and the second trigger signal are generated; the voltage measurement circuit can receive the first trigger signal and the second trigger signal. When the second trigger signal is used, the output voltage of the filter capacitor is sampled and measured to obtain the first output voltage signal and the second output voltage signal; the first output voltage signal and the second output voltage signal can be processed by the processing module to obtain the filter capacitor capacity and ESR. Further, the monitoring circuit for monitoring the output filter capacitor of the switching power supply module to be tested is greatly simplified, and the monitoring cost is reduced.

In a specific embodiment, the first transition edge signal is a rising edge signal; the second transition edge signal is a falling edge signal.

Specifically, the rising edge signal refers to the signal of the control signal at the control signal terminal at the rising edge time. The falling edge signal refers to the signal of the control signal at the control signal terminal at the falling edge time. When the first transition edge signal is a rising edge signal, the first trigger signal is generated by the trigger circuit and transmitted to the voltage measurement signal, and the first output voltage signal is obtained through the voltage measurement circuit. When the second transition edge signal is a falling edge signal, a second trigger signal is generated through the trigger circuit and transmitted to the voltage measurement signal, and the second output voltage signal is obtained through the voltage measurement circuit. The first output voltage signal and the second output voltage signal are processed by the processing module to obtain the capacity and ESR of the filter capacitor. Only the rising edge signal and the falling edge signal of the control signal can be obtained, and the output voltage signal can be obtained twice. The capacity and ESR of the filter capacitor can be quickly monitored, which improves the monitoring efficiency.

In a specific example, the first transition edge signal may be a falling edge signal, and the second transition edge signal may be a rising edge signal. Similarly, only the rising edge signal and falling edge signal of the control signal can be obtained, and the output voltage signal can be obtained twice, so that the capacity and ESR of the filter capacitor can be quickly monitored, and the monitoring efficiency can be improved.

In a specific embodiment, as shown in FIG. 3 , it is a schematic diagram of a specific structure of an embodiment of an apparatus for monitoring the output filter capacitance of a switching power supply according to the present invention. The device includes a trigger circuit 310 , a measurement circuit (ie, a voltage measurement circuit) 320 and a processing module 330 . in:

Trigger circuit: It is mainly used to generate the output voltage sampling trigger signal of the switching power supply module to be tested, so as to realize the acquisition of the output voltage at a specific moment (the first transition edge signal and the second transition edge signal).

Measuring circuit: sample the AC component of the output voltage of the switching power supply module to be measured, and obtain the output voltage ripple signal.

Processing module: process the voltage data collected by the measurement circuit, and calculate the filter capacitor capacity C and ESR of the switching power supply module to be tested.

Specifically, the switching power supply module to be tested (Buck (step-down) type power supply module) realizes the control of the output voltage by adjusting the ratio of the turn-on and turn-off time of the switch tube (transistor) circuit M1. Since M1 is in the on and off state, the current path will change, and ripple will be generated on the output voltage, which will affect the subsequent circuits. For a fixed load R2, the power supply output ripple is related to the capacitance C and ESR of the filter capacitor C1. Therefore, by sampling the ripple signal, the capacity C and ESR of the filter capacitor C1 can be calculated, so as to monitor the state of the filter capacitor of the switching power supply module to be tested. By using the switching signal change of the switch tube of the switching power supply module to be tested as the trigger signal for measurement, the complexity of the trigger circuit is greatly reduced, and the application convenience of the measurement is improved.

It should be noted that, in addition to Buck-type power supply modules, the switching power supply module to be tested can also be Boost (boost) type power supply modules, Buck/Boost (buck/boost) type power supply modules, and Cuk-type power supply modules. module, Sepic type power module or Zeta type power module, etc.

In order to more specifically illustrate the difference between the embodiment of the present invention and the traditional switching power supply output filter capacitor monitoring, the specific working process of the embodiment of the switching power supply output filter capacitor monitoring device shown in FIG. 3 is as follows:

1. After the power module works normally, the average output voltage remains in a stable state. At this time, the control signal CP is a square wave signal, and the duty cycle is determined by the ratio of the input voltage to the output voltage.

2. On the rising edge of CP, after input to the trigger circuit, the trigger circuit will generate a trigger signal (Trigger).

3. The Trigger signal controls the ADC module to sample and obtain the measurement output signal.

4. The measurement output signal is sent to the processing module for storage, and the data record is A. At this time, the corresponding ripple voltage is U(0), that is: U(0)=A/S-Uc, where S is the measurement circuit transformer module. Method multiples, Uc is the potential difference between the left and right sides of the transformer in the measurement circuit.

5. After the falling and rising edges of CP are input to the trigger circuit, the trigger circuit will generate the trigger signal Trigger.

6. The Trigger signal controls the ADC (Analog-to-Digital Converter) module to sample and obtain the measurement output signal.

7. The measurement output signal is sent to the processing module for storage, and the data record is B. At this time, the corresponding ripple voltage is U(D), namely: U(D)=B/S-Uc.

8. Through the data U(0) and U(D), the capacity C and the ESR resistance R _esr of the filter capacitor C1 can be calculated.

In a specific embodiment, as shown in FIG. 4 , it is a schematic structural diagram of a trigger circuit of an embodiment of a switching power supply output filter capacitance monitoring device according to the present invention. The trigger circuit includes a trigger 410, an XOR 420 and a delay 430;

The first input terminal of the flip-flop 410 is connected to the signal output terminal of the XOR, the first output terminal is connected to one end of the delayer 430, and the second output terminal is connected to the second input terminal of the flip-flop 410; The signal input end is connected to the control signal end of the switching power supply module to be tested, the second signal input end is connected to the other end of the delayer 430 ; the signal output end of the XOR 420 is connected to the signal input end of the voltage measurement circuit.

Specifically, the first input end of the flip-flop 410 is connected to the signal output end of the XOR, the first output end is connected to one end of the delayer 430, and the second output end is connected to the second input end of the flip-flop 410; The first signal input end of 420 is connected to the control signal end of the switching power supply module to be tested, the second signal input end is connected to the other end of the delay 430; the signal output end of the XOR 420 is connected to the signal input end of the voltage measurement circuit. Therefore, the control signal of the switching power supply module to be tested is input to the first signal input terminal of the XOR 420 , and the trigger signal can be output from the signal output terminal of the XOR 420 .

For example, when the first signal input terminal of the XOR 420 receives the first transition edge signal, the first transition edge signal passes through the transition of the flip-flop 410 and the delay device 430, and the signal output terminal of the XOR 420 Output the first trigger signal; when the first signal input terminal of the XOR 420 receives the second transition edge signal, the second transition edge signal passes through the transition of the flip-flop 410 and the delay device 430, and the XOR 420 The signal output terminal outputs the second trigger signal. By using the switch control signal of the switching power supply module to be tested as the trigger source, the complexity of the trigger circuit is greatly simplified.

In a specific embodiment, the flip-flop is a D flip-flop, a JK flip-flop or an RS flip-flop.

Specifically, when the flip-flop is a D flip-flop, the CP terminal (trigger input terminal) of the flip-flop is connected to the signal output terminal of the XOR, the Q terminal (signal output terminal) is connected to one end of the delayer, and the Q terminal (reverse terminal) The signal output end) is connected to the D end (signal input end) of the trigger; the first signal input end of the XOR is connected to the control signal end of the switching power supply module to be tested, and the second signal input end is connected to the other end of the delayer; The signal output end of the OR is connected to the signal input end of the voltage measuring circuit. When the flip-flop is a JK flip-flop or an RS flip-flop, the JK flip-flop or the RS flip-flop can be converted into a D flip-flop to realize the corresponding function.

It should be noted that a conventional flip-flop conversion method can be used to convert a JK flip-flop or an RS flip-flop into a D flip-flop, and the connection relationship between the JK flip-flop or the RS flip-flop and other module devices will not be described again here.

In a specific embodiment, as shown in FIG. 5 , it is a schematic diagram of the specific structure of the trigger circuit of the embodiment of the switching power supply output filter capacitor monitoring device of the present invention. The trigger circuit may include an XOR gate, a D flip-flop, and a delay unit. The input signal CP of the trigger circuit comes from the control signal of the switching power supply module to be tested (the control signal controls the switching on and off of the switching power supply module of the switching power supply module to be tested). The trigger signal Trigger can be obtained by XORing the delay amount of the output Q of the CP and the D flip-flop. Preferably, the delay unit may be constituted by several buffers, and the delay amount of the delay unit may be determined by the timing requirements of the enable signal of the voltage measurement circuit. Therefore, the jump of the control signal of the switching power supply module to be tested can be used as the trigger signal for measurement, which greatly reduces the complexity of the trigger circuit, reduces the monitoring cost, and improves the convenience of measurement.

The traditional measurement of the filter capacitor of the switching power supply module to be tested uses the output voltage signal for a special node for sampling. There are strict requirements for the trigger clock signal of the sampling circuit, especially for the time measurement at half of the switching duty cycle, which can easily lead to inaccurate measurement time, affect the calculation and measurement accuracy, and further complicate the design of the trigger circuit.

However, the trigger circuit of the embodiment of the present invention can use the jump of the control signal of the switching power supply module to be tested as the trigger signal for measurement, which greatly reduces the complexity of the trigger circuit and improves the application convenience of measurement.

In a specific embodiment, as shown in FIG. 6 , it is a schematic structural diagram of a voltage measurement circuit of an embodiment of a switching power supply output filter capacitance monitoring device according to the present invention. The voltage measurement circuit may include an acquisition module 610 .

The control end of the acquisition module 610 is connected to the signal output end of the trigger circuit, the input end is connected to the output end of the filter capacitor, and the output end is connected to the processing module.

Specifically, the control end of the acquisition module 610 is connected to the signal output end of the trigger circuit, the input end is connected to the output end of the filter capacitor of the switching power supply module to be tested, and the output end is connected to the processing module. Therefore, when the acquisition module 610 inputs the trigger signal (the first trigger signal or the second trigger signal), the filter capacitor of the switching power supply module to be tested is subjected to voltage sampling, and the sampling signal (the first output voltage signal or the second output voltage signal) can be output. . Preferably, the acquisition module 610 may be an ADC acquisition module. Therefore, only one set of acquisition modules 610 can be used to acquire the filter capacitance of the switching power supply module to be tested, thereby simplifying the monitoring circuit.

In a specific embodiment, as shown in FIG. 6 , the voltage measurement circuit may further include an amplifier 620 .

The input end of the amplifier 620 is connected to the output end of the filter capacitor, and the output end is connected to the input end of the acquisition module.

Specifically, the input end of the amplifier 620 is connected to the output end of the filter capacitor of the switching power supply module to be tested, and the output end is connected to the input end of the acquisition module. Thus, the signal can be maintained and the driving capability of the output signal can be improved.

In a specific embodiment, the amplifier is an isolated amplifying module or a non-isolated amplifying module.

Specifically, the amplifier can be an isolation amplifier module, which can isolate DC and reduce the noise interference of the input signal; the amplifier can also be a non-isolation amplifier module, which can directly measure the output voltage signal of the filter capacitor of the switching power supply module to be tested, thereby further simplifying the monitoring circuit.

In a specific embodiment, the isolation amplifier module is a transformer isolation amplifier module or an optocoupler isolation amplifier module.

Specifically, the transformer isolation and amplification module can be composed of a transformer and a basic amplifier. The output voltage signal of the filter capacitor of the switching power supply module to be tested is isolated from noise and DC through the transformer, and the signal is followed by the basic amplifier to improve the driving ability of the output signal. The optocoupler isolation amplifier module can be composed of an optocoupler isolation chip and a basic amplifier. The output voltage signal of the filter capacitor of the switching power supply module to be tested is isolated from noise and DC through the optocoupler isolation chip, and the signal is followed by the basic amplifier to improve the output signal. Drive capability.

In a specific embodiment, as shown in FIG. 7 , it is a schematic diagram of the specific structure of the voltage measurement circuit of the embodiment of the switching power supply output filter capacitance monitoring device of the present invention. The voltage measurement circuit may include a transformer, an amplifier Ap and an ADC acquisition module. The input end of the transformer receives the output voltage of the switching power supply module to be tested. The output voltage is isolated from DC through the transformer, and the AC signal is amplified. The amplified AC signal is amplified and output at equal times through the amplifier Ap. The output signal is sampled by the ADC acquisition module. The sampling moment of the ADC acquisition module can be determined by the Trigger (first trigger signal and second trigger signal) signal. The sampled digital signal is transmitted to the subsequent processing module.

In a specific embodiment, as shown in FIG. 8 , it is a schematic flowchart of Embodiment 1 of the method for monitoring the output filter capacitance of a switching power supply according to the present invention. Include the following steps:

Step S810, receiving the first output voltage signal and the second output voltage signal transmitted by the voltage measurement circuit; the first output voltage signal is generated by the voltage measurement circuit after receiving the trigger circuit according to the first transition edge signal of the switching power supply module to be tested. When the first trigger signal is used, the output voltage of the filter capacitor is sampled and measured; the second output voltage signal is the second output voltage signal generated by the voltage measurement circuit after receiving the trigger circuit according to the second transition edge signal of the switching power supply module to be tested. When the trigger signal is triggered, the output voltage of the filter capacitor is sampled and measured.

Step S820, processing the first output voltage signal and the second output voltage signal to obtain the capacity and ESR of the filter capacitor.

Specifically, the processing module can receive the first output voltage signal and the second output voltage signal transmitted by the voltage measurement circuit; and can quickly obtain the capacity and ESR of the filter capacitor by processing the first output voltage signal and the second output voltage signal. Thus, the monitoring capability of the state of the switching power supply module to be tested is effectively improved.

In a specific embodiment, the first transition edge signal is a rising edge signal; the second transition edge signal is a falling edge signal.

In a specific embodiment, taking the monitoring of the Buck-type power supply module in FIG. 3 as an example, the specific processing process of the processing module is as follows:

The output ripple can be expressed as:

Among them, U(0) is the ripple voltage on the rising edge, U(D) is the ripple voltage on the falling edge, D is the duty cycle of the control signal (the ratio of the ON time of the switch M1 to the entire cycle), and U _o is the output Voltage average value, f _s is the frequency of the control signal, L is the inductance value of the switching power supply module to be tested, C is the capacity of the filter capacitor C1, and R _esr is the ESR resistance value of the filter capacitor C1.

From the above formula, it can be concluded that the capacitance C of the filter capacitor C1 and the R _esr of the ESR are:

Preferably, in order to improve the calculation accuracy, the data record values U(0) ₁ , U(0) ₂ , U(0) ₃ . . . U(0) _n at multiple rising edge moments can be measured; The data record values U(D) ₁ , U(D) ₂ , U(D) ₃ . . . U(D) _n at the edge instants. Among them, n represents several rising or falling edge moments, and the average value is calculated:

Wherein, i represents one of 1 to n rising or falling edge times. And use the mean to replace the immediate value (U(0) and U(D)), that is, the calculation method is as follows:

In the above embodiments of the switching power supply output filter capacitor monitoring method, the capacity and ESR of the filter capacitor can be quickly obtained by processing the received first output voltage signal and the second output voltage signal. The monitoring cost is reduced, and the monitoring capability of the state of the switching power supply module to be tested can be effectively improved.

The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be regarded as the scope described in this specification. Those of ordinary skill in the art can understand that all or part of the steps in the methods of the above embodiments can be completed by instructing the relevant hardware through a program, and the program can be stored in a computer-readable storage medium, and the program can be executed when the program is executed. At the time, it includes the steps described in the above method, and the storage medium, such as: ROM/RAM, magnetic disk, optical disk, etc.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are more specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims (10)

1. a switching power supply output filter capacitance monitoring device, is characterized in that, comprises trigger circuit, voltage measurement circuit and processing module; The input end of described trigger circuit connects the control signal end of the switching power supply module to be tested, and the output end connects the described a signal input end of the voltage measurement circuit; the measurement input end of the voltage measurement circuit is connected to the output end of the filter capacitor of the switching power supply module to be tested, and the measurement output end is connected to the processing module; The trigger circuit transmits the first trigger signal generated according to the first transition edge signal input by the switching power supply module to be tested to the voltage measurement circuit; the voltage measurement circuit receives the first trigger signal When , sampling and measuring the output voltage of the filter capacitor, and transmitting the obtained first output voltage signal to the processing module; The trigger circuit transmits the second trigger signal generated according to the second transition edge signal of the switching power supply module to be tested to the voltage measurement circuit; when the voltage measurement circuit receives the second trigger signal , sampling and measuring the output voltage of the filter capacitor, and transmitting the obtained second output voltage signal to the processing module; The processing module processes the first output voltage signal and the second output voltage signal to obtain the capacity and ESR of the filter capacitor; Wherein, the trigger circuit includes a trigger, an XOR and a delay device; The first input end of the flip-flop is connected to the signal output end of the XOR, the first output end is connected to one end of the delayer, and the second output end is connected to the second input end of the flip-flop; the The first signal input end of the XOR is connected to the control signal end of the switching power supply module to be tested, the second signal input end is connected to the other end of the delayer; the signal output end of the XOR is connected to the voltage Signal input of the measurement circuit. 2 . The device for monitoring the output filter capacitance of a switching power supply according to claim 1 , wherein the first transition edge signal is a rising edge signal; the second transition edge signal is a falling edge signal. 3 . 3. The switching power supply output filter capacitance monitoring device according to claim 1 or 2, wherein the trigger is a D trigger, a JK trigger or an RS trigger. 4. The switching power supply output filter capacitance monitoring device according to claim 1 or 2, wherein the voltage measurement circuit comprises an acquisition module; The control end of the acquisition module is connected to the signal output end of the trigger circuit, the input end is connected to the output end of the filter capacitor, and the output end is connected to the processing module. 5. The switching power supply output filter capacitance monitoring device according to claim 4, wherein the voltage measurement circuit further comprises an amplifier; The input end of the amplifier is connected to the output end of the filter capacitor, and the output end is connected to the input end of the acquisition module. 6 . The switching power supply output filter capacitance monitoring device according to claim 5 , wherein the amplifier is an isolated amplifying module or a non-isolated amplifying module. 7 . 7 . The switching power supply output filter capacitance monitoring device according to claim 6 , wherein the isolation amplifying module is a transformer isolation amplifying module or an optocoupler isolation amplifying module. 8 . 8. A switching power supply output filter capacitance monitoring method based on the switching power supply output filter capacitance monitoring device according to claim 1, characterized in that, comprising the following steps: Receive the first output voltage signal and the second output voltage signal transmitted by the voltage measurement circuit; the first output voltage signal is generated by the voltage measurement circuit after receiving the trigger circuit according to the first transition edge signal of the switching power supply module to be tested When the first trigger signal is received, the output voltage of the filter capacitor is sampled and measured; the second output voltage signal is obtained by the voltage measurement circuit after receiving the trigger circuit according to the first trigger signal of the switching power supply module to be tested. Obtained by sampling and measuring the output voltage of the filter capacitor when the second trigger signal is generated by the second transition edge signal; The first output voltage signal and the second output voltage signal are processed to obtain the capacity and ESR of the filter capacitor. 9 . The method for monitoring the output filter capacitance of a switching power supply according to claim 8 , wherein the first transition edge signal is a rising edge signal; the second transition edge signal is a falling edge signal. 10 . 10. A computer-readable storage medium on which a computer program is stored, characterized in that, when the computer program is executed by a processor, the steps of the method of claim 8 or 9 are implemented.

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