A Digital Exponential Wave Generator with Variable Time Constant

Abstract

The invention provides a variable time constant digital exponential wave generator comprising a frequency divider, an encoder, a one-in-four channel selector and an exponential generation circuit. The input of the frequency divider is a clock signal clk and a demagnetizing time signal TD generated by an oscillator. The frequency divider performs frequency division on the output of the oscillator so that four charge and discharge signals of clk, 1 / 2clk, 1 / 4clk and 1 / 8clk are obtained and connected with the four input ends of the channel selector respectively, and the counting result acts as the input signal of the encoder to realize encoding. A counter starts counting after conduction of a switching tube until the counting result is reset to zero at the conduction instant of the switching tube in the next cycle and then starts counting again. The encoder encodes the signal according the size of conduction time. The encoded signal directly controls conduction and disconnection of the channel selector. The output of the channel selector controls the charging frequency of the exponential generator. The gradually multiplying time constant of exponential waves can be obtained by switching of different frequencies of signal channels.

Description

technical field [0001] The invention relates to an AC / DC converter, in particular to a variable time constant digital exponential wave generator, which can obtain a wider load regulation range when the AC / DC converter outputs a constant voltage. Background technique [0002] With the continuous improvement and rapid development of microelectronics technology, breakthroughs have been made in switching power supply technology. Switching power supply has become the key to high efficiency, low power consumption, safe and reliable operation of various electronic equipment and systems. Switching power supplies can be divided into two types: isolated and non-isolated according to whether the input and output are isolated. The non-isolated type mainly includes four structures including buck converter, boost converter, buck-boost converter and Cuk converter. The isolated switching power supply is generally isolated by a transformer without power frequency. There are five common str...

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Problems solved by technology

[0005] The implementation principle of the triangular wave constant voltage control method is simple, but it cannot meet the high requirements of wide load regulation range when the system is in constant voltage mode

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