Analysis of UC3846 Indirect Current Type Control

1 Introduction

The current mode control mode is a high performance control technology that has many advantages over conventional voltage type control. This control has significant advantages over traditional peak and average current mode control in terms of noise sensitivity and dynamic range; it reduces control complexity in linear adjustment and wide load range adjustment, and resolves system static accuracy and stability. The contradiction makes the system have the characteristics of fast dynamic response and high static precision. Voltage integration indirect current type control will be more and more adopted by users and manufacturers.

2. Indirect current type control technology

Conventional current-mode control is usually based on sampling the inductor current, while indirect current-type control does not require a resistor or Hall element to sample the current, but instead reconstructs the inductor current by integrating the inductor's voltage to achieve indirect sampling of the current. In this way, not only the loss due to the sampling resistor and the excessive clutter signal can be avoided, but the circuit is turbulent, and the transformer is not needed, which makes the implementation of the current-type control scheme simpler. More importantly, since the introduced voltage integral feedback can follow changes in the input voltage and output voltage, the performance of the system has significant advantages.

Figure 1 shows the schematic diagram of the indirect current-mode controlled Boost converter with Boost converter as an example. Here, the Boost circuit is set to operate in a continuous state.

Figure 1 Indirect current type control Boost converter

In the figure, uL—the voltage across the secondary winding of the boosting inductor L (for ease of analysis, set the primary and secondary coil turns ratio N=1)

When the switch VQ is turned on and off, uL is Ui and Ui-Uo, respectively. The triangular wave output to the integrator is:

It can be seen from equations (1) and (2) that us is proportional to iL' and has the same change rule, so it can actually characterize iL. The rising and falling slope of us is also related to the input voltage and output voltage. When the input voltage or output voltage changes, it will directly cause the change of the us slope, so that the turn-off time of the drive pulse signal changes, thereby adjusting the duty cycle. The role of D. Figure 2 shows the duty cycle adjustment of the indirect current mode control.

Figure 2 Indirect current type control duty cycle adjustment

TWS Headset

This TWS Headset including many private design, Apple Airpods, Wheat straw Eco friendly headset, all high qualty with competitive price.

Tws Headset,Wireless Sports Headset,Tws Wireless Headset,Wireless Headset Earbuds

Shenzhen GEME electronics Co,.Ltd , https://www.gemesz.com