SU104207A1 - Static power converter - Google Patents

Description

A feature of the proposed device for power conversion, containing, like the known devices of the same designation, multiplying and phase-sensitive circuits, is the multiplication circuit in the form of a voltage divider consisting of ohmic resistance and thermal resistance of indirect heating, which ensures an increase in the accuracy of power measurement. For temperature compensation, it is envisaged that the indirect heating of the thermal resistance of the direct heating should be connected in series with the indicated thermal resistance.

FIG. 1 shows a schematic diagram of the proposed device for a single-phase network; in fig. 2 is a multiplying circuit entering this device; in fig. 3 is a diagram of an apparatus for power conversion of a three-phase network.

The device (Fig. 1) includes: a conventional phase-sensitive circuit and a multiplying circuit.

The multiplying circuit (Fig. 2) is a voltage divider consisting of a thermal resistance CT of indirect heating, shunted by resistance RI, and a series-connected ohmic resistance k.

Dependence Consideration

RT f (In)

the thermal resistance values from the current In passing through the preheater R shows that the voltage drop across the resistance R. j can, under certain conditions, be made proportional to the change of the current In. On the other hand, it is obvious that the voltage drop across the resistance But is proportional to the voltage U applied to the circuit (if only the current IT flowing through the thermal resistance is small enough and does not change its temperature). Thus, the voltage Ops at the output of the circuit is connected with the voltage and at the input and the current Ip of the heater Kn as follows: U, ibix k and In

and the multiplying properties of the circuit become osequal (k is the coefficient of proportionality, taking into account the parameters of the multiplying circuit).

It is easy to show that at a small value of the current IT flowing through a thermistor (maximum value I, must lie within the line of its section of the current-voltage characteristic), the multiplying circuit is shown in FIG. 2, can produce multiplication with an accuracy of P / o with an In current varying by + 20% of the nominal value.

The dependence of the characteristic on the temperature of the surrounding air can be fully compensated by the introduction of a second thermal resistance R TI (thermal resistance of the direct heating), which, as shown in FIG. 1, together with the resistances R, and RJ constitute the temperature compensation circuit.

The fault of the circuit with temperature compensation when the temperature changes by 20 ° does not exceed P / o.

Across the Net and Ice ™ in FIG. 1 k and 1 p k ki k, ICCT

where k k kj k. ,, t. e. the output voltage of the converter is proportional to the active power of the network.

The capacitance Cf, a bypass winding of the transformer, is introduced to compensate for the initial phase shift in the phase-sensitive circuit.

Capacity C and resistance H

introduced to reduce the dynamic error of the power converter.

The delay in the preheater circuit with voltage-induced voltage changes, determined by the constant thermal resistance time, can be reduced by introducing a compensating

the values are respectively the voltages of the voltage transformer and the current transformer, which are related proportionally to the voltage and current of the measured network.

In the embodiment shown in FIG. 1, the power converter circuit multiplying circuit is used in such a way that the voltage UCCTH is supplied to the heater circuit R of the thermal resistance RT of the multiplying circuit through the resistance R o and. In this case, the heater current is equal to:

n M UcCTH)

where k | - coefficient of proportionality, taking into account the parameters of the heater circuit.

The value, proportional to the value of the current ICCTH multiplied by the cosmic value obtained using the phase-sensitive circuit, is applied as a voltage U to the input and multiply the circuit:

and K2 ICCTH COS ccTHj

where k2 is the coefficient taking into account the parameters of the phase-sensitive circuit. Thus, the output voltage of the multiplying circuit is:

UCCTH COS-fccTn k-nets)

chains C R, as shown in FIG. one.

The introduction of dynamic compensation is permissible only if the load in the measured network cannot change abruptly, since an abrupt change in load causes additional errors due to the introduced RgC value.

FIG. Figure 3 shows a device for power conversion of a three-phase network consisting of two semi-sets A and B, each of which contains one semiconductor thermal resistance of indirect heating RT and is

the circuit shown in FIG. 1. The currents and voltages supplied to the half sets of A n B are indicated

letters: Gss ™, iset ,,, Gee ™, and-ssti.

The subject matter of the invention is 1. A static power converter comprising a multiplying circuit with a non-linear element and a phase-sensitive circuit, which also, in order to improve the accuracy of the power conversion, as

A voltage divider consisting of ohmic resistance and semiconductor thermal resistance of indirect heating is applied to the multiplying circuit.

2. In the device according to claim 1, use for temperature compensation thermal resistance of direct heating, connected in series with resistance of indirect heating.