SU1269247A1 - Method of generating pulse-width modulated pulse sequence - Google Patents

Abstract

The invention relates to a pulse technique and can be used in low frequency key amplifiers and controlled voltage converters. The aim of the invention is to expand the modulation frequency range. This is achieved in that, according to the method, the input signal and the feedback pulse signal are integrated, a reference signal is generated, the rate of change of which increases linearly over the period of its repetition by the amplitude ratio of the feedback pulse signal. to a constant integration time, compare the result of the integration with the reference signal and form a sequence of pulses, the duration of which is proportional to the result with avneni, a repetition period equal to the repetition period of the reference signal. The formation of a reference signal of a specific form allows to increase the depth with to feedback, thereby reducing distortion of the amplitude and phase (L frequency characteristics of devices using the early method, as well as reducing the distortion of the output signal in the upper frequency range by eliminating harmonic low frequency components 1. to O5 SO x 4

Description

The invention relates to a pulse technique and can be used in low frequency key amplifiers and controlled voltage converters.

The aim of the invention is to expand the modulation frequency range by generating a special shaped reference signal.

The drawing shows a timing diagram of the formation of a pulse width modulated pulse sequence.

t

The method of forming a pulse-width modulated sequence involves integrating the output signal and a pulse feedback signal, generating a reference signal whose rate of change increases linearly over the period of its repetition by a ratio of the amplitude of the feedback pulse of a constant integration time, comparing the result of integration with the reference signal. sigigipom and the formation of a sequence of pulses, the duration of which is proportional to the result of the comparison, and Heat-repetition period equal to the repetition of the reference signal.

An output pulse-width modulated pulse sequence is used as the feedback pulse signal.

The reference signal U is formed in such a way that its speed during the repetition period varies linearly from the initial value to the maximum value.

dUo. . d

+ B (t).

(1) dt

The use of a cross section of a pulse width modulated pulse sequence allows one to significantly reduce the distortion of the output signal in pulse width modulators due to the nonideality of their key elements. However, the pronounced frequency dependent nature of the main signal (feedback loops in modulators using this method of forming, leads to a significant distortion of the output signal in the upper frequency range. Low frequency (LF) is the ratio of the output pulse voltage Ui, in such Properties are defined by the following expression

t

K ,, (and - and „) - -1- J (pE -, Mj,) dt

l - i "

 V, -,

(2)

one

GG - integrator transmission coefficient of the harmonic signal of frequency Q;

1- constant integration time;

The amplitude of the reference voltage.

in the left part (2) of the ratio | „„ ЬЕ (,) У „,

- Ujdc (3)

where v ,,

Hopi- ied E.

The low frequency components of the output pulse voltage lead to the appearance of harmonic components in the spectrum of the pulse sequence.

The magnitude of the harmonic components increases in proportion to the increase in the feedback depth and the increase in the frequency V of the input signal. When the reference signal changes during the switching period T from zero to the specified value V,. the law of its change can be defined by the following expression:

) -b b (-b) l,

(four)

AT VT2 where a ---; b - ----.

In this case, the reduction (2) with regard to (3) and (4) can be written in the following form:

. to fv - V) & --- (1 - V) V ,,

) vv vj,; 2 vi

V

(five)

 (a + bV) V V

and uv

Claims (1)

where V ---; V. --- - according to S5J bb. Normally normalized to the magnitude of the input signal and the value of the LF components on the load. From expression (5) it follows that the BI-I value is L – j; ---, it is possible to compensate components, V, and thereby eliminates harmonic low frequencies from the output pulsed to voltage spectrum. This makes it possible to significantly reduce distortion of the output signal in the upper frequency range. IskazheNIN in this case are determined only by the presence in the spectrum of the pulse signal of combinational components penetrating into the upper frequency range of the low frequency signal. The magnitude of these coefficients at - 0.1% () does not exceed 2%. In addition, the formation of the reference signal in accordance with expression (4) allows a significant increase in the maximum permissible value of the feedback factor, while it is necessary that the rate of change of the control signal at the time of the control pulse is equal to - V ,, not exceeded the rate of change of the reference voltage -: - - A + Sun ,,. Whence dt, in the limiting case (ripH), get where p is the limiting feedback coefficient. Thus, the formation of a reference signal of a special form related to the amplitude of the pulse sigA, 4 feedback and constant integration of this signal and the input signal is allows you to almost double the depth of feedback, reducing the resultant distortion of the amplitude and phase-frequency characteristics of devices using the proposed method, as well as reduce the distortion of the output signal in the upper frequency range by eliminating harmonic low frequency components. All this, in turn, allows to expand the frequency range of modulation devices using the proposed method. Claim Method A method for generating a width-modulated pulse sequence, including integrating an input signal and a pulse signal of a feedback signal, comparing the received signal with a reference signal with a constant repetition period and generating a sequence of pulses whose duration is proportional to the result of the comparison, and the repetition period is equal to the repetition period of the reference signal. signal, characterized in that, in order to expand the modulation frequency range, the rate of change of the reference signal for the period of its repetition linearly increases the magnitude ratio feedback pulse signal amplitude to integration time constant.