DATA COMPRESSING METHOD AND DATA READING-OUT METHOD FOR DATA TABLE, AND PHASE CALCULATING METHOD FOR ALTERNATING-CURRENT ELECTRIC MOTOR DRIVING CURRENT USING THE SAME

摘要

PURPOSE:To decrease the number of data in the data table while securing necessary precision by compressing the data so that an input data range corresponding to the same output data becomes wider as an input increases. CONSTITUTION:When the data table of a function which monotoneously increase or decrease in output or decreases in the variation quantity of the output as the input increases is generated, the data are so compressed that the input data range corresponding to the same output data becomes wider as the input increases. In this case, when the variation range of the input data is 0-Xmax and the compression number of data is (n), the field of an address X of the data table is referred to as it is in a range of 0-Xmax/2n, but in a range of Xmax/2n-Xmax, the field of an address (Xmax/2n+1XK+(X/2k) of the data table is referred to when X=Xmax/2n-k+1-Xmax/2n-k (K=1, 2...n). Consequently, the number of data in the data table can be decreased while the necessary precision is secured.