SU1653105A1 - Method fro controlling bridge servoinvertors with output lc filters - Google Patents

Abstract

The invention relates to electrical engineering and can be used to control the converter with a given output parameter curve (voltage or current). The purpose of the invention is to reduce switching losses by reducing the switching frequency and improving the dynamic characteristics. The converter contains a valve switch 2 connected to voltage source 1 and through a filter inductance to load 4 or LC filter capacitance Z. The switch (for example, a bridge inverter) is made on controllable gates, which can be used as transistors or lockable thyristors. , accepting the information about the variable states of the sensors 5-7, the task signal to the output variable from the task block 8, and outputting the control pulses through the intermediate the first amplifier 10 to the switch 2a Valve kommutator2 transducer positioned at three positions corresponding opredelennomusostoyaniyu valves (two positions of vanishing aktivnyei) and perehodiz one position to another osuschestvlyaetsyapo The projected results of calculating the values of the variable rassoglasovaniyavyhodnoy 1 or S (L

Description

ABOUT)

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The invention relates to electrical engineering and can be used to control a converter with a predetermined output parameter curve (voltage or current) about.

The purpose of the invention is to reduce switching losses by reducing the switching frequency and improving the dynamic characteristics,

The drawing shows the structure of the follower converter controlling the proposed method "

The converter contains a wired switch 2 connected to the source 1, connected through a filtering inductance to an LC filter capacitor 3 or load 40. The switch (for example, a bridge inverter) is made on controlled vents which can be used as transistors or lockable thyristors. Information about the variable states from the sensors 5-7 and the reference signal from the output variable from the reference block 8 are received by the calculator 9, which issues control pulses through the intermediate amplifier 10 to the switch op 20

The control method of the converter is as follows.

The mismatch 641 is calculated) (the difference between the output variable and the task for a certain time interval ahead, equal in this case to the duration of the modulation cycle h.

When calculating the forecast, it is assumed that the next switch occurs at the moment t (time is counted from the moment of the last switch). As a result, the calculating unit generates a switch function s (t) that uniquely determines the switch position and switch points, tsv position change. The first active position s +1 corresponds to the state of the switch when one gate of the anode group and one gate of the cathode group of the bridge circuit are turned on; at the second active position s -1, other valves of the anodic and cathodic groups are turned on; at the zero position, s o, two anodic and cathodic group fans are included. During the operation of the bridge inverter, the load is applied to the power supply voltage with a V or - sign, respectively, and in the zero position, the output voltage

switch is zero. The transition from one position to another is carried out when the mismatch prediction assumes a zero or minimum value.

s -sign 5 „

The prediction of the mismatch is calculated using the formulas obtained by solving a system of differential equations for a converter with a three-position YIM. The forecast is the sum of the components, one of which is determined by the current values of the state variables (the free component f) and the other - expected switch positions (forced component w):

5 f +,

where s takes -values +1, -1, 0 "mismatch prediction when ot-

The current is determined by the formula

Ј i (h - t) .- T,

where i (h-t) i is (h-t) the average value of the current during the forecast interval (t, h); u is the input voltage; e is the load voltage; L is the inductance of the filter; i - current task. When exiting from an active position to a position of zanula, the forecast function coincides with the free component

Ј f i - i - (h - t).

Two possible positions when moving out of the nulling state correspond to a pair of forecast functions:

b f + s -w:

 i i

w o

2L

(ht)

The free component f is inside the zone (+ w0; -WQ); monotonously tapering with a change in local time t; when f reaches one of the zone boundaries, switching occurs:

f + wq o f - wfl o

s "1; s -1,

When applying the proposed method, the mass and size parameters of the filter are approximately halved and, consequently, the efficiency increases. The application of the method is effective in building a system to which high operational requirements are imposed (for example, work with nonlinear load, good dynamics, high efficiency, etc.)

Claims (1)

Invention Formula A bridge servo inverter control method with an output LC filter, which consists in generating a current command signal iy, measuring the input voltage, and outputting it, setting the time interval for L, the inductance of the output filter, calculating the difference and the sum of the free and forced components, control the values of the free component and the calculated differences and sums, and at the time when the condition f 0 switches the valves from the first active position to the zero position, at the time when condition, the valves switch from the position by the hour of h, equal to the estimated duration of the modulation cycle of the output voltage of the inverter, set the first active position of the valves, which includes one ventilator to the second active position, anode type and one cathode valve at the moment of time when the second active position is executed in groups, with condition Ј Z 0, the valves switch out of the second active position to the eanulenic position, and at the moment of time when the condition f + w 0 is satisfied, the valves switch from the zeroing position which include other valves of the anode and cathode groups, and the position of the Zeros, in which both vents of the anodic or cathodic group are turned on, and the valves are switched from one position30 v.first active position „ five 0 In another, they differ in that, in order to reduce switching losses and improve the dynamic characteristics, simultaneously with performing the switching kadoy, the local time t begins to count, the free component f and the forced component w of the mismatch prediction w are calculated by the formulas fi ( h - t) - i; w u (h - t) / 2L, where L is the inductance of the output filter, calculates the difference and the sum of the free and forced components, controls the values of the free component and the calculated differences and sums, and at the time when the condition f 0 switches the valves from the first active position to the zero position, at the moment of time, to the second active position, at the moment of time when the condition, Z 0 is fulfilled, the valves switch from nor, when the condition is fulfilled, the valves switch from the zeroing position to the second active position, at the time when the condition Ј Z 0 is fulfilled, the valves switch from thirty v.first active position „