Method for determining RMS values for grid-linked converters
AssigneeBallard Power Systems Inc.
InventorAnil Tuladhar
Life of this patent
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Abstract
Techniques for determining root mean square (RMS) values of a signal for controlling operation of grid-linked converters, such as DC-to-AC inverters, via squaring the signal, sampling the squared signal n times during a cycle period to obtain n samples, summing the first n−1 samples to obtain a first value, multiplying the first value by a sampling time and a frequency of the signal to obtain a second value, determining a compensation factor, adding the compensation factor to the second value to obtain a third value, and determining a square root of the third value to obtain a RMS result.
Claims30
A method of determining a root mean square (RMS) of a signal for controlling operation of a converter, the method comprising:
- squaring the signal;
- sampling the squared signal n times during a cycle period to obtain n samples;
- summing the first n−1 samples to obtain a first value;
- multiplying the first value by a sampling time and a frequency of the signal to obtain a second value;
- determining a compensation factor;
- adding the compensation factor to the second value to obtain a third value;
- and
- determining a square root of the third value to obtain a RMS result.
A processor-readable medium storing instructions for causing a processor to determine a root mean square (RMS) of a signal by:
- sampling the signal n times during a cycle period to obtain n samples;
- squaring the first n−1 samples to obtain n−1 squared samples;
- summing the n−1 squared samples to obtain a first value;
- multiplying the first value by a sampling time and a frequency of the signal to obtain a second value;
- determining a compensation factor;
- adding the compensation factor to the second value to obtain a third value;
- and
- determining a square root of the third value to obtain a RMS result.
An electric power system to transform power between a power grid and a power source, the electric power system comprising:
- a converter;
- at least one switch selectively operable to electrically couple the converter to the power grid in a first state and to electrically uncouple the converter from the power grid in a second state;
- and
- a controller coupled to control the converter and the at least one switch, the controller configured to determine a root mean square (RMS) of a signal associated with the power grid by:
- squaring the signal;
- sampling the squared signal n times during a cycle period to obtain n samples;
- summing the first n−1 samples to obtain a first value;
- multiplying the first value by a sampling time and a frequency of the signal to obtain a second value;
- determining a compensation factor;
- adding the compensation factor to the second value to obtain a third value;
- and
- determining a square root of the third value to obtain a RMS result.
Dependencies are inferred from the claim text.