DE2950340C2 - DC voltage converter for the stabilized power supply of telecommunications equipment - Google Patents

Description

T =

+ s-2-dfTi + l)

that the two corner frequencies v \ and τι are so close to each other that the desired frequency response of the phase results, which means:

Γ k

T \ Tl

dl

Transfer function
static reinforcement

reciprocal base frequency 1
reciprocal base frequency 2
Degree of damping 1
Degree of damping 2

The invention relates to a DC / DC converter for a stabilized power supply using communications technology Devices according to the preamble of the claim.

For the power supply of communication devices with stabilized voltages, pulse-width-regulated ones are used Forward and flyback converters used. The switching transistors are controlled with pulses constant frequency and variable width. The pulse width is determined by a pulse width controller by comparison the output voltage is regulated with a setpoint value so that the output voltage is constant. Since the closed control loop in the sieve chain contains phase-rotating low-pass filters, difficulties arise in practice with regard to the stability of the control loop, and the optimization of such circuits with regard to the Stability requires considerable experimental effort.

A DC / DC converter with the basic circuit according to FIG. 1 has a typical frequency response Phase and the amount of the loop gain according to FIG. 2 on. For a stable regulation it is desirable that the phase assumes a high positive value over the largest possible frequency range. the end F i g. 2, the critical control range can be recognized by the fact that the phase is only very slightly ahead.

From the journal Frequency 31 (1977) 4, p. 96 to 100 and 31 (1977) 5, p. 153 to 156 there is an article »Stabilisitätsuntersuchungen on pulse-width-controlled forward and flyback converters «by Erich Pivit. the DC voltage converters described therein also have a very high frequency range from 200 to 600 Hz eerinee Dositive Phase on.

These DC voltage converters all have the disadvantage that, for many applications, the control speed is too low is achieved because the stability for higher frequencies due to insufficient phase lead is not guaranteed

The invention is based on the object of providing a DC / DC converter of the type mentioned at the beginning specify who works at a higher control speed and has a greater stability reserve, see above that input voltage disturbances can be regulated better than it was previously known.

The object is achieved as described in the characterizing part of the claim.

The invention is explained in more detail below with reference to the figures.

F i g. 3 shows a block diagram of an arrangement according to the invention,

F i g. 4 shows an embodiment of a compensation amplifier,

Fi g. 5 shows the typical frequency response of the magnitude and phase of the gain of the compensation amplifier according to FIG. 4,

F i g. 6 shows the magnitude and phase of the loop gain of a DC / DC converter according to the invention.

Switching the inductance on and off in the power circuit results in voltage peaks that are important for the Output voltage are very disturbing. Therefore, a low-pass filter is switched in the output, which the high frequencies short-circuits contained in the voltage spikes. This will largely reduce the output voltage smoothed. Since the Ausgar> gssigna! superimposed on this ripple, it is for the derivation of the Controlled variable required that the 'tapped output voltage is smoothed again with the help of an integrator before it is fed to the comparator. Because even small interference voltage peaks influence the comparator so strongly that an exact regulation of the Pulse width for the switching pulses of the controlled switch is no longer possible.

However, these measures have the disadvantage that they reduce the frequency response of the phase of the Affect loop gain negatively with regard to the stability of the entire control loop; compare to this F i g. 2.

The main idea of the invention is to switch on a compensation amplifier between the integrator and the comparator correct the frequency response of the phase of the loop gain so as to that a sufficient stability reserve is obtained and thus the control speed is increased significantly can be.

The frequency response of the phase of the loop gain necessary for this is obtained with the aid of a feedback compensation amplifier according to the claim, if the two corner frequencies η and Ti are brought together correspondingly close. The phase reserve that can be achieved with this is relatively high.

For this purpose 3 sheets of drawings

Claims (1)

Claim: DC / DC converter for the stabilized power supply of communications equipment, consisting of from a power circuit, a controlled switch connected upstream of this, as well as a one Integrator forming a control loop with a downstream comparator controlling the switch, wherein between the integrator and the comparator a high positive in the rule-critical frequency range Phase having compensation amplifier is switched on, characterized in that that the compensation amplifier is fed back via a multiple K-C-Giied, so that the following Laplace transformed transfer function gives: