Digital compensator for power supply applications

A state estimator for a switching power supply, the state estimator comprising:

• a high dynamic range digital to analog converter (DAC) that receives an estimated output voltage obtained by multiplying an estimated state vector by an output matrix;
• an analog subtraction component that subtracts an output of the high dynamic range DAC from a measured output voltage;
• an analog to digital converter (ADC) that receives an output of the analog subtraction component;
• a first delay component that receives the estimated output voltage;
• a first addition component that adds an output of the ADC and an output of the first delay component;
• and
• a first subtraction component that receives an output of the first addition component and the estimated output voltage,
• wherein an output of the first subtraction component is a voltage error utilized in obtaining the estimated state vector.

A duty cycle determination system for a switching power supply, the duty cycle determination system comprising:

• a first multiplier that receives an inductor current estimate and that multiplies the inductor current estimate by a first gain;
• a subtraction component that receives a capacitor voltage and a predetermined voltage reference value, and that provides a difference between the capacitor voltage and the predetermined voltage reference value;
• a second multiplier that receives state vector elements other than capacitor voltage and an output of the subtraction component, and that multiplies the received state vector elements and the output of the subtraction component by a second gain vector;
• a first combining component that combines an output of the first multiplier and an output of the second multiplier, and that provides a negative of a sum of the output of the first multiplier and the output of the second multiplier;
• a third multiplier that receives the inductor current estimate and that multiplies the inductor current estimate by a third gain;
• an addition component adds an output of the first combining component and an output of the third multiplier, and that provides a sum of the output of the first combining component and the output of the third multiplier;
• a reciprocal component that receives a power stage input voltage and that provides an inverse of the power stage input voltage as output;
• and
• a fourth multiplier that multiplies an output of the reciprocal component and an output of the addition component,
• wherein an output of the fourth multiplier is the duty cycle.

A method for estimating inductor current in a switching power supply, the method comprising:

• using a processor:
• obtaining an average of a switch voltage at an input to the switching power supply;
• obtaining an average of an output voltage of the switching power supply;
• obtaining a difference between the average of the switch voltage and the average of the output voltage;
• multiplying the difference by a first model parameter to obtain a first product;
• multiplying a delayed value of a previously estimated inductor current by a second model parameter to obtain a second product;
• adding the first product and the second product to obtain a sum;
• and
• obtaining an estimated inductor current from the sum.

A method for measuring inductor current in a switching power supply, the method comprising the steps of:

• using a processor:
• measuring an inductor voltage;
• providing a pole-zero for a pole-zero filter;
• selecting a zero of the pole-zero filter to compensate for an external anti-aliasing filter;
• selecting a pole of the pole-zero filter to match an inductor time constant;
• filtering the measured inductor voltage with the pole-zero filter;
• and
• multiplying an output of the pole-zero filter by a predetermined filter gain.