Method and device for generating pulse-width modulated signals, comprises additional loop with pointer, test-circuit and overflow register, connected from counter to comparator

摘要

The method for generating a pulse-width modulated control signal (SC) from a reference signal (SREF) includes incrementing a counter (CPC) which produces incremented numbers (NB) at each pulse of a clock signal, obtaining a reference number each time the counter (CPC) attains an initialization value, computing an overflow bit (OVF) by comparing a value of a pointer (PO) to a reference parameter (PARA), and producing the control signal (SC) by comparing the incremented number (NB) delivered by the counter (CPC) to a realized comparison word comprising the overflow bit as the high-value bit and the realized reference number as the low-value bit. The incremented number (NB) and the reference number are of the same size (N). The comparison word is a sample of the reference signal (SREF) associated with the pointer value, and the reference number is obtained by removing the high-value bit of the sample of the reference signal. The reference number is obtained by multiplying an initial number by an amplitude-modulation (MA) parameter, where the initial number is obtained by removing the high-value bit of the sample of the reference signal. The reference parameter is a pointer value having a maximum amplitude, or the reference parameter is a set of pointer values each having a maximum amplitude. A generator of pulse-width modulated signals, comprises a counter (CPC), a reference memory (MR), a comparison register (RC), a pointer (PO), a test circuit (CTEST) for delivering the overflow bit, an overflow register (RD), and a comparator (CPT) delivering the control signal (SC). The comparison register (RC) and the counter (CPC) area of the same size (N). The test circuit (CTEST) contains a comparator with two inputs for the parameter (PARA) and the pointer value. The generator also comprises an index register (RI) for storing the amplitude-modulation parameter, and a multiplication circuit with one input connected to the index register and the other input to the reference memory (MR). A monophase device, for example of motor or waveform generator type, is controlled by a circuit comprising the generator. A three-phase device is controlled by a circuit comprising three generators operating in parallel and utilizing the same counter (CPC).