Rectifier-based analog load system circuit diagram

GW MB10F 0.8A 1000V rectifier bridge

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

Overview:
Generally, DC power supplies need to be tested for aging test and power output characteristics before leaving the factory. In developed countries, analog test systems are generally used for similar tests to return the energy of the test process to the grid. Since such systems are generally expensive, only a very small number of power supply manufacturers in China use electronic analog power loads during factory inspections.
For some occasions, the discharge of the power supply can also be realized by an active inverter circuit composed of thyristors. However, due to its poor power factor and high harmonic content, it cannot meet the relevant international and national harmonic standards, and thus is not suitable for large Power applications.

In order to solve this problem, we have developed an electronic analog power load using a voltage-type PWM rectifier. It is designed and implemented using power electronics technology, computer control technology and power system automation technology to evaluate various DC power supplies. Experimental device for the test. Although the electronic analog load system implemented by the voltage type PWM rectifier can perform the power supply system test of the constant voltage output, the DC power supply and the battery power supply whose output voltage varies within a certain range (the terminal voltage gradually decreases during the discharge process), because the voltage The PWM side has a step-down characteristic from the DC side to the AC side, so it is difficult to design an electronic analog power load using a voltage type PWM rectifier to meet the output voltage drop when the output voltage of the tested power supply is low or the battery is discharged due to discharge. The entire range of requirements.

Aiming at the above analysis, an electronic analog power load system using the boosting characteristics of the current and PWM converters is proposed by comparing the characteristics of the voltage and current type PWM rectifiers. In addition to the advantages of high power factor and continuous output adjustment of the voltage-type PWM rectifier, the system can also meet the test requirements of the power supply with varying output voltage, and has the advantages of high reliability.

Comparison of characteristics between voltage-selective PWM rectifier and current-mode PWM rectifier

Although both voltage-type PWM rectifiers and current-mode PWM rectifiers can convert AC to DC and DC to AC energy, they have their own characteristics due to their different circuit configurations. From the perspective of the filter structure, the two have dual characteristics, as shown in Table 1.

Table 1 Characteristics of voltage-type PWM rectifiers and current-mode PWM rectifiers

Reasons for using a current-mode PWM rectifier For a test power supply with a constant output voltage, a voltage-type PWM rectifier can well meet the requirements of the test system. However, for the case where the output voltage of the tested power supply is not constant, due to the DC of the voltage-type PWM rectifier. The side voltage should be greater than or equal to the peak value of the AC side voltage. From the perspective of satisfying the test requirements well, it is difficult to realize the design of the rectifier. For example, the voltage range of the DC power source under test is 20%~100% of the rated voltage. If the rated voltage of the AC is designed according to the rated voltage of 20%, the AC current will be very large when working at 100% of the rated voltage; if it is designed according to the rated voltage of 100%, the inverter will be connected to the Internet when the DC voltage is low. The current will become more and more severely distorted as the DC voltage decreases. For the battery test, since the output voltage drops during discharge, it has the same properties as the power supply with the output voltage change. It can be seen from the above analysis that in this case, the current analog load is realized by the current type PWM rectifier, and the feedback power of the experimental power can be conveniently realized.

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