Voltage feed-forward compensation and voltage feedback compensation for switched mode power supplies

摘要

A digital control unit generates a control signal to control a duty cycle of a switched mode power supply such that a faster response to an input voltage transient is achieved. The digital control unit comprises a feedback compensator, a feed forward compensator, a transient detector, and a controller. The transient detector receives a signal indicative of the input voltage of the switched mode power supply and detects transients on the received signal. The feedback compensator receives a signal indicative of the output voltage of the switched mode power supply and adjusts the control signal. The feed forward compensator receives a signal indicative of the input voltage of the switched mode power supply, performs a relatively fast, but coarse, adjustment of the control signal, and then performs a more accurate, but relatively slow, adjustment of the control signal.

主权项

1. A method of generating a digital control signal for controlling a duty cycle of a switched mode power supply, the method comprising:
receiving a signal indicative of an input voltage of the switched mode power supply; receiving a signal indicative of an output voltage of the switched mode power supply; detecting a transient on the received signal indicative of the input voltage of the switched mode power supply; and in response to the detection of said transient: performing a voltage feedback adjustment of a control signal for controlling the duty cycle of the switched mode power supply by adjusting the control signal in dependence upon the signal indicative of the output voltage; in a first stage of feed forward compensation, performing a coarse voltage feed forward adjustment of the control signal for controlling the duty cycle of the switched mode power supply by setting a value of the control signal to a first value derived by performing a first at least one bit shift operation on the value of the control signal; and in a second stage of feed forward compensation, performing a more accurate voltage feed forward adjustment of the control signal for controlling the duty cycle of the switched mode power supply by setting the value of the control signal to a second value calculated in dependence upon the signal indicative of the input voltage of the switched mode power supply; wherein the first and second stages of the feed forward compensation are performed such that the control signal is set to the first value derived in the first stage before the control signal is set to the second value calculated in the second stage.