UC2842: Slope compensation calculation

Hi Jerry,

Slope compensation is used to keep current mode control stable for D>0.5. It adds an artificial ramp signal to the measured current signal.

Some resources for current mode control are:

1) PRACTICAL CONSIDERATIONS IN CURRENT MODE POWER SUPPLIES

2) Understanding and Applying Current-Mode Control Theory (ti.com)

3)Ramp Compensation for Current-Mode Converters | Electronic Design

These equations are used to determine the amount of slope compensation needed to stabilize the converter using current mode control. It uses information of the inductor current slope to calculate the amount of additional slope compensation to maintain the ideal quality coefficient Qp = 1.

Let me know if this helps.

Thanks,

Joseph

Hi Joseph,

Thanks for your explanation.

The pictures of Ramp Compensation for Current-Mode Converters | Electronic Design can not be loaded and this article doesn't mention the detail definition of Q. So could you pls explain more about how Q is defined and how the equation is derived.

Thanks a lot, looking forward to your reply.

Hi Jerry,

Q is defined from the derivation of the control-to-output transfer function.

Check this reference for the definition: CurrentModeControl.pdf (ridleyengineering.com) (pages 121 - 123). 

Thanks,

Joseph