SU785778A1 - Converter of ac voltage or alternating current effective value into dc voltage - Google Patents

Description

connected to the common supply diagonal bridges.

The drawing shows a circuit diagram of a proposed converter of an effective value of an alternating voltage or a current into a direct voltage.

The device contains two automatically balanced bridges. The main bridge is formed by a thermoresistor yes If 2 and resistors 3, 4, Thermo resistor 1 and resistors 3, 5, 6 are included in the additional bridge. An unbalance amplifier 7 is connected to the output diagonal of the main bridge and an unbalance amplifier 8 is connected to the OUTPUT diagonal of the additional bridge. Both amplifiers are direct current amplifiers. A preheater 9, functionally connected to a thermistor 1, is connected to a convertible parameter circuit (AC voltage, or current), and to an output circuit of an amplifier 8 with a voltage Ue - a heater 10 acting on a thermistor 2. The output of an amplifier 7 is connected to the common supply diagonal posts. The additional bridge is self-balanced due to the presence at the output of the amplifier 7 of the initial mixing voltage.

The operation of the device is based on stabilizing the temperature of thermistors 1 and 2 of indirect heating, which helps to eliminate the influence of non-linearity and non-identity characteristics of thermistors, as well as to increase the linearity of the common characteristics of the converter.

The temperature of each of the thermistors 1 and 2 is determined by the ambient temperature and the temperature rise of the thermometer due to direct and indirect heating.

It can be shown that the resistance of thermistor 1, corresponding to the equilibrium of the additional bridge, will always be constant, since the resistors 3, 5 and 6 are constant. Consequently, the temperature of thermistor 1 is also unchanged, i.e. regardless of the specific value of its components listed above, their sum is automatically kept constant due to the balance of power generated by the currents in the preheater 9 and in the body of the thermistor 1. The same is true

and for the main bridge, where the temperature of thermistor 2 remains unchanged.

It is established that if the ambient air temperature for both thermistors is maintained at the same level and to ensure equality of the resulting temperatures of the thermistors, then the constant voltage Uo at the output of the converter will correspond to the linear function of the effective value of the transformed parameter, for example, alternating voltage,

.

° | b, -T1

10 l

where JJg, (- the heat transfer coefficients of the heaters 9 and 10;

20Rq, - resistances of heaters 9 and 10.

In order to maintain the equality of the ambient temperatures of the thermistors and to keep the coefficient constant. 25 C, all elements of the transformer circuit must be thermostatically controlled,

Claims (1)

Invention Formula Actual value of alternating voltage or current to direct voltage containing two coupled resistive bridges, one of which includes thermoresistors connected to the zero potential bus in one of the arms, unbalance amplifiers, inputs of which are connected to the output diagonal of the bridge, thermistor heaters one of which is included in the circuit of the parameter being converted, and the other to the output circuit of the first unbalance amplifier, characterized in that, in order to simplify and increase the reliability of operation, The output of the second unbalance amplifier is connected to the common supply bridge diagonal switch. Information sources," taken into account in the examination 1, Patent of Germany 1814520, class, 21 e 19/02, 1968. 2, Richman P, A new widebeind true RMS / DC converter - IEEE Internal Convent. Nah 1966, 14,  10, p.2-7.