A USB port powered product radiated emission test system

Abstract

The utility model discloses a USB port power supply product radiation emission test system, including direct current source, filter, impedance stabilizing network, direct current source is used for converting commercial power into DC5V output, and through the filter, the interference of output end is filtered and then is accessed to the wave darkroom, and then through the short line is connected to the positive and negative electrode input end of passive device impedance stabilizing network, and is output through the USB port, and the impedance matching network is used for providing the uniform standard impedance for the measured equipment connected with its USB port through the USB line. The utility model through the wave darkroom isolation direct current source's interference, and the filter has filtered out the interference of direct current source output end, and after direct current is introduced into the wave darkroom, through the short line connection to the impedance stabilizing network, and the short line can reduce the interference from direct current source as far as possible, and the impedance stabilizing network is passive device, and itself does not produce the interference, and can provide the uniform standard impedance for the sample, to guarantee the consistency of test result from the whole.

Description

Technical Field

[0001] This utility model relates to the field of electromagnetic compatibility, specifically to a radiated emission testing system for USB port powered products. Background Technology

[0002] In recent years, more and more home appliances, lighting fixtures, information technology equipment, and medical products have adopted built-in battery power, and manufacturers do not include AC power adapters in the sales process. Testing and certification bodies need to provide a separate power supply when testing, certifying, and conducting random inspections of these products to assess the radiated emissions of the samples in charging mode. Currently, three power supply solutions are known: power bank, AC power adapter, and DC power. The power bank power supply solution involves placing the power bank and sample in an anechoic chamber, with the sample connected to the lithium battery in the power bank via a USB cable. The AC power adapter power supply solution involves placing the AC power adapter and sample in an anechoic chamber, with the AC power supplied by the AC mains power in the chamber and then converted to DC output. The DC output port of the adapter is connected to the sample via a USB cable. The DC power supply solution involves placing a programmable DC power source outside the anechoic chamber, with DC power entering the chamber through an anechoic chamber filter, and adjusting the output voltage of the DC power source to match the sample power supply.

[0003] The disadvantage of the AC power adapter solution is that the power adapter itself introduces interference, affecting the test results. This is due to the principle of current power adapters, which use PWM control and are highly susceptible to electromagnetic interference. The principle of the programmable DC power supply is similar to that of the AC power adapter solution; even when placed outdoors in an anechoic environment, the output of the programmable DC power supply is still very susceptible to electromagnetic interference. While the power bank solution introduces limited electromagnetic interference during discharge, the inability to provide a stable impedance to the sample in actual testing (the internal resistance of different power banks varies, ranging from 100mΩ to 300mΩ) can lead to significant differences in test results between different institutions due to variations in brand and specifications.

[0004] In summary, existing radiated emission testing systems for USB-powered products cannot maintain consistent test results. Utility Model Content

[0005] The purpose of this invention is to provide a testing system that can improve the consistency of radiation emission testing of USB-powered samples.

[0006] The technical solution adopted by this utility model is as follows: A radiated emission test system for USB-powered products includes a DC source, an anechoic chamber filter, and an impedance stabilization network. The DC source is used to convert the mains power into DC 5V output. After filtering out the interference brought out by the output end through the anechoic chamber filter, it is connected to the anechoic chamber. Then, it is connected to the positive and negative input terminals of the passive device impedance stabilization network through a short wire and output through the USB port. The impedance matching network is used to provide a uniform standard impedance for the device under test connected to its USB port through a USB cable.

[0007] The short wire mentioned in this utility model refers to a wire with a length range of less than 40cm.

[0008] Preferably, the impedance stabilization network structure is as follows:

[0009] The impedance matching network consists of resistors R1 and R2 and capacitor C. Capacitor C is connected in parallel between the positive and negative input terminals, while resistors R1 and R2 are connected in series with capacitor C on the positive and negative lines, respectively, and then connected to the positive and ground leads of the USB port. This impedance matching network not only provides a uniform standard impedance but also further filters out interference signals at the output of the anechoic chamber filter.

[0010] Preferably, the resistance values ​​of resistors R1 and R2 are both 100mΩ, and the capacitance value of capacitor is 10mF.

[0011] Beneficial effects:

[0012] This utility model's testing system places the DC source outside the anechoic chamber, isolating it from interference. The DC 5V output from the DC source is connected to the anechoic chamber through a filter, which also filters out interference from the DC source's output. After the DC power is introduced into the anechoic chamber, it is connected to an impedance stabilization network through a short wire. The short wire minimizes interference from the DC source. The impedance stabilization network is a passive device that does not generate interference itself, and it provides a uniform standard impedance for the samples, thus ensuring the consistency of the test results as a whole. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the connection structure when using the USB port powered product radiated emission testing system of the preferred embodiment of this utility model for testing;

[0014] Figure 2 This is a schematic diagram of the principle of the radiated emission test system for USB-powered products using a preferred embodiment of the present invention (the anechoic chamber filter between the current source and the impedance stabilization network is omitted in the figure). Detailed Implementation

[0015] Example 1

[0016] This embodiment of the USB-powered radiated emission testing system includes a DC power source, an anechoic chamber filter, and an impedance stabilization network. The DC power source converts AC mains power to a 5V DC output. After filtering out interference from the output end by the anechoic chamber filter, it is connected to the anechoic chamber. It is then connected via a short cable to the positive and negative input terminals of the passive device impedance stabilization network, and output through the USB port. The impedance matching network provides a uniform standard impedance for the device under test connected to its USB port via a USB cable. Typically, the power supply to the anechoic chamber is located at the center of the turntable. The impedance stabilization network is placed on the turntable floor of the anechoic chamber, drawing power from the center of the turntable. The short cable length should ideally be less than 40cm, with 30cm to 40cm being recommended.

[0017] The connection diagram during testing is as follows: Figure 1 As shown.

[0018] In this embodiment of the test system, the DC source is placed outside the anechoic chamber, isolating the interference from the DC source itself. The DC 5V output from the DC source is connected to the anechoic chamber through a filter, which can also filter out the interference brought out by the DC source output. After the DC power is introduced into the anechoic chamber, it is connected to the impedance stabilization network through a short wire. The short wire is used to minimize the interference from the DC source. The impedance stabilization network is a passive device that does not generate interference itself. On the other hand, it can provide a uniform standard impedance for the sample, thereby ensuring the consistency of the test results as a whole.

[0019] The impedance stabilization network in this embodiment is as follows: Figure 2 As shown, the impedance matching network consists of resistors R1 and R2 and a capacitor C. Capacitor C is connected in parallel between the positive and negative input terminals. Resistors R1 and R2 are connected in series with capacitor C on the positive and negative lines, respectively, and then connected to the power positive and ground leads of the USB port. This impedance matching network not only provides a uniform standard impedance but also further filters out interference signals at the output of the anechoic chamber filter. In this embodiment, the resistance values ​​of resistors R1 and R2 are both 100mΩ, and the capacitance value of the capacitor is 10mF.

[0020] This does not mean that the impedance matching network of this invention can only adopt the above-described resistor and capacitor structures, or can only take the values ​​described above; it is merely a recommendation. Those skilled in the art should understand that the impedance stabilization network described here aims to provide a uniform standard impedance for the device under test, ensuring that the impedance matching networks of various test systems used can achieve this purpose.

Claims

1. A USB port powered product radiated emission test system, characterized in that, It includes a DC power source, an anechoic chamber filter, and an impedance stabilization network. The DC power source converts the mains power into a DC 5V output. After filtering out the interference brought out by the output terminal through the anechoic chamber filter, it is connected to the anechoic chamber. Then, it is connected to the positive and negative input terminals of the passive device impedance stabilization network through a short wire and output through the USB port. The impedance matching network is used to provide a uniform standard impedance for the device under test connected to its USB port via a USB cable.

2. The test system of claim 1, wherein, The impedance stabilization network structure is as follows: It consists of resistors R1 and R2 and capacitor C. Capacitor C is connected in parallel between the positive and negative input terminals. Resistors R1 and R2 are connected in series in the positive and negative lines after capacitor C, respectively, and then connected to the power positive and ground leads of the USB port.

3. The test system of claim 2, wherein, The resistance values ​​of resistors R1 and R2 are both 100mΩ, and the capacitance value of capacitor is 10mF.

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