RU2565577C2 - Method to control key converters of direct voltage into direct one - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to conversion equipment. The method to control key converters of direct voltage into direct one, comprising an inductive element in an output filter or in an inductive energy accumulator. To traditional modes of converter operation: increase and decrease of energy in the inductive element, two additional modes are added - storage of the upper level of accumulated energy and storage of the lower level, during which energy storage in the inductive element is not changed.

EFFECT: elimination of output voltage surges and depressions during quick reach to the mode, and under spasmodic variation of load parameters.

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Description

The present invention relates to methods for controlling key DC-to-DC converters of switching power supplies [Polikarpov A.G., Sergienko E.F. Switching regulators and DC / DC converters // M .: Publishing House of MPEI, 1998].

From the current level of technology, DC-to-DC converters with direct coupling (step-down, step-up, inverting regulators) and their transformer analogs are known: step-down regulator (linear push-pull and push-pull voltage converters), step-up regulator [Borovikov V.M., Krasnikov Yu.V. . Switching voltage regulator of a step-up type with a continuous output current and an extended range of regulation of the output voltage (options). Patent RU No. 2299511 C1, H02M 3/335, 10.26.2005] and a step-down regulator (single-cycle flyback converters).

The traditional way of controlling the converter implies the presence of two modes (states). The first mode is the accumulation of energy in the magnetic field of the inductive element (or the accumulation of energy in the magnetic field of the inductive element with the simultaneous transfer of energy to the load) when the keys are open. The second mode is the transfer of energy to the load (or the transfer of energy to the load and a dead time) when the keys are locked. To implement two modes of operation, one key is enough.

One of the main disadvantages of this control method is the poor dynamic properties of the converter of the switching power supply, namely the occurrence of overshoot of the output voltage when the converter is turned on, as well as spikes and dips in the output voltage when the load parameters change abruptly.

The problem to which the invention is directed, is to improve the dynamic properties of the Converter switching power supply.

This problem is solved due to the fact that additional modes of operation of the converter are introduced - storage of the upper and lower energy levels in the inductive element. The introduction of additional modes requires the use of at least two keys in the converter circuit. If the converter is single key, then it is necessary to use an additional key and a complete change in the control algorithm. If the converter is made on two or more keys, then only a change in the control algorithm is possible.

The technical result provided by the given set of features is the introduction of two additional modes - storage of the upper level of accumulated energy and storage of the lower level, during which the energy supply in the inductive element does not change.

The invention is illustrated by drawings, which depict:

figure 1 - step-down voltage regulator;

figure 2 - increasing voltage regulator;

figure 3 - inverting voltage regulator;

figure 4 - transients when you turn on the Converter;

figure 5 - transients in the mode of discharge / surge load in the step-down voltage regulator.

It is convenient to consider the processes occurring in the regulators with direct connection (Fig.1-3), since the regulators and their analogues work identically.

Common to the three types of regulators is that, firstly, after opening the key, an increase in energy occurs in the inductive element. The increase in energy of the inductive element of the lowering controller is accompanied by the simultaneous supply of energy to the load. In boosting and inverting regulators this effect is not observed.

Secondly, when closing the key, the amount of energy in the inductive element decreases. In this case, the step-down and inverting controllers receive the energy stored in the inductive element in the load. At the increasing regulator, the total energy accumulated in the inductive element and supplied by the source enters the load.

Lowering, raising and inverting regulators have similar dynamic characteristics. Therefore, it is convenient to consider transients with an abrupt change in the load parameters using the example of one of the regulators, in particular, a lowering regulator (Fig. 1).

In the aforementioned controller in steady state, the average current through the inductive element is equal to the average load current. When the load parameters change abruptly, dips or surges of the output voltage occur, accompanied by a damped oscillatory transient at the self-oscillation frequency of the LC filter (Fig. 4).

You can eliminate this effect by introducing storage modes. The introduction of additional modes requires the installation of another key shunting the inductive element.

Thanks to the additional key, it is possible to provide an excess supply of energy in the inductive element and eliminate the output voltage drop with an abrupt increase in the load current, and also at the right time to stop the flow of energy into the load, thereby eliminating the output voltage spikes during the abrupt load shedding (Fig. 5).

Similar transients occur in boosting and inverting controllers with the only difference that the attenuation of the emissions is aperiodic. The introduction of storage modes eliminates the above negative effects.

The foregoing applies to continuous current mode (RHT). In the particular case, in the regime of discontinuous currents (RPT), only the storage of the upper energy level remains, the lower level corresponds to the absence of energy in the inductive element. Therefore, when working in the RPT, only emissions are eliminated, and voltage dips cannot be eliminated.

Claims (1)

A method of controlling key DC-DC to DC converters containing an inductive element in the output filter or in an inductive energy storage device, which consists in the fact that in such converters, depending on the state of the switches, two operating modes are used: the first is accompanied by an increase in energy in the inductive element, the second is its reduction, characterized in that two additional modes are introduced - storage of the upper level of accumulated energy and storage of the lower level, during which the energy reserve AI in the inductive element does not change.

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