SU760437A1 - Power digital-analogue converter - Google Patents

Description

The invention relates to a converter technique and can be used in voltage regulators, in electric drive systems and tracking systems of direct and alternating current.

The power digital-to-analog converter is known: a converter containing a digital driver, a digital comparison nivage device, a digital-analog converter, a preamplifier, an output amplifier, a motor, an encoder, a circuit for limiting the level of the voltage switching circuit. The output amplifier is connected via a preamplifier to the output of a digital-to-analog converter through a preamplifier, and a second input through a sequentially connected supply voltage switching circuit and a level limiting circuit to the output of the digital input converter, whose input is connected to the output 25 of the digital comparator. The first input of the comparing digital device is connected to the master device, and the second input is connected to the encoder installed on ba2

Lu motor, anchors winding which is connected to the output amplifier £ 1}.

Such a converter provides a reduction in power dissipation in the output amplifier with a decrease in the error signal, but has the following disadvantages.

Three independent power sources are connected in series one after another, creating only three voltage levels at the amplifier input, they are controlled not from a digital code, but from a multi-element level limiting circuit. With medium and large error signals, the amplitude of the ripple voltage at the armature of the motor with pulse-width regulation is equal to the value of the supply voltage, as a result of which the power loss increases both in the power transistors of the output amplifier and in the motor.

The closest technical solution to the present invention is a power digital-to-analog converter containing a computing device, a converter “code-width-pulse-modulated signal (code-PWM converter) with

four

760437

two inputs and two outputs, a power reversing converter, a pulse generator, a zero-organ, a trigger, and two thyristor switches. Converter code-PWM one input connected to the output of the pulse generator, and the other with the output of the computing device. Transducer outputs “code-PWM” 'Connected to the inputs of the thyristor switches that control the operation of the thyristors of a power reversing converter of the bridge type, the inputs of which are connected to the outputs of the trigger _> whose inputs are connected to the output of a null organ fed from an AC network [23.

The disadvantages of this converter are large ripple output voltage, the amplitude of which

<0

15

equal to the voltage value of the power source. This causes significant power losses in the key elements of the converter 20 and additional power losses in the load. The lack of compensation for the voltage drop in the power supply and the power converter leads to instability of the output voltage.

The purpose of the invention is to increase the stability of the output voltage, reducing the power loss on switching in the power elements of the converter and additional power losses in the load.

This is achieved by the fact that in the silo ¹ howl digital to analog converter,

containing a computing device, an impulse generator, a code-width-pulse-modulated signal converter with two inputs and two outputs; a pulse generator connected to one of the code-40 pulse-width modulated signal input of the converter, a trigger with two separate inputs, a power reversing converter and a comparator, a 45 “code-voltage” measuring converter, a sawtooth voltage generator, a threshold device and a low-pass filter were introduced, reobrazovatel "code-voltage" output coupled to a first input zd roystva Device for comparison, a second input coupled through a low pass filter

. _{YOU O} D _{OM of a} power reversing converter and an output through an amplifier and a regulator with the first input of a threshold device, the second input of which is connected via a sawtooth voltage generator to the first output of a code-width-pulse-modulated signal converter, the second output connected to the first input 60 of the trigger, the second input of which is connected to the output of the threshold device, the first output of the computing device, which contains the most significant bits of the binary code, is connected to the first 65

the input of the power pre-amplifier and the first input of the code-converter converter, the second output of the computing device h -... low-order bits, is connected to the second input of the measuring converter and to the first input of the converter code-width-pulse-modulated signal, the second input of which is connected to the output of the master oscillator, and the third output of the computing device, which serves as a sign bit of code, is connected to the second input of the power converter, the third input of which is connected to the output mentioned th trigger.

FIG. 1 is a block diagram of the proposed converter ¹ ; FIG. 2 - timing diagrams of switching the main elements of the converter.

The converter contains a computing device 1 with three outputs, a code-voltage measuring transducer 2, a power reversing converter 3, a low-pass filter 4, a comparison device 5 with two inputs and one output, an amplifier 6, a regulator 7, a threshold device 8 with two inputs and one output, a sawtooth voltage generator 9, a code-width-pulse-modulated signal converter 10 with two inputs and two outputs, a trigger 11 with two split inputs and a master pulse generator 12.

The first output 13 of the computing device 1, containing t high bits of the binary code, is connected to the first input of the power converter 3 and to the first input of the measuring converter 2, the second output 14, containing η-νη low-order bits, is connected to the second input 15 of the measuring converter 2, and with the first input of the code-PWM converter, and the third output 16, which serves as a significant code discharge, is connected to the second input of the power converter 3. The comparator 5 with the first input 17 is connected to the output of the measuring converter 2, the second input 18 through the low-pass filter 4 to the output of the power converter 3, and the output to the amplifier 6. The output of the amplifier 6 through the regulator 7 is connected to the first input 19 of the threshold device 8, the second input 20 of which is connected to the output of the sawtooth voltage generator 9 Converter "KODSHIM" 10 second input connected to the master pulse generator 12, the first output 21 to the input of the sawtooth generator 9, the second output 22 to the first input of the trigger 11. The second input 23 of the trigger 11 is connected to the output of the threshold device 8. Out Trigger 11 is connected to

five

760437

6

the third input 24 of the power Converter 3.

The Converter operates as follows.

At the first input of the comparator 5 receives a reference voltage 5

, obtained with high accuracy at the output of the measuring transducer 2, and at the second input 18 - the output voltage 0 ^, ^ of the low-pass filter 4. Difference Λΐΐ = - Ob. ^ e- ^ d

the cut amplifier 6 and the regulator 7 are fed to the first input 19 of the threshold device 8, the second input 20 of which is connected to the output 21 of the code-PWM converter via the sawtooth voltage generator 9. At the output of the last, the duration of the pulses, following with the switching frequency, is proportional to the code value of the pt

. low-order bits at the output 14 of the computing device 1. 20

The signal at output 22, corresponding to the beginning of each pulse, arrives at the first input of the trigger, and the signal at output 21, corresponding to the end of the pulses within the switching period 25, starts the sawtooth generator 9. At the same time, the output voltage of the sawtooth voltage generator 9 and the voltage at output 19 of the regulator 7 30

triggered device 8 is triggered and flips 11 trigger 11 on input 23 to the state ensuring the formation of the trailing edge of the control pulse. Relative value 35

the pulse duration at the output of the trigger 11 is determined by the sum of the signals at inputs 22 and 23. The operation of the power reversing converter 3 is controlled by two ^ d channels: digital (outputs 13 and 16) and digital-analog (input 24).

The dynamic characteristics of the digital-to-analog converter are determined by the selected control law. In the case when regulator 7 is an integrator or a proportional-integral link, the duration of the pulses at the output of trigger 11 at a constant repetition frequency will increase or decrease depending on the sign of the LI. Changes will occur until di becomes zero. Thus, the output voltage is stabilized at the 55 level specified by the computing device. The speed of the power reversing converter in the “large” is determined by the speed of the digital channel (inputs 13 and 1Y), and the speed of 60 in the small channel is determined by the digital-analog channel (input 24) of the control.

The operation of the power reversing converter is explained by temporary

diagrams (fig. 2) at change 65

input five-bit binary code according to a linear law with the initial value of the code - 00100. Zzshtoiho-. The bath areas in FIG. 2 correspond to one in a particular code bit.

The ripple level of the output voltage 11 ^, the power converter 3 does not exceed any code combination at the input, as a result of which the power losses for switching the power transistors are significantly reduced. A decrease in the ripple level of the output voltage leads to a decrease in the amplitude of the current ripple and a significant reduction in the additional power loss due to these current ripple.

The output voltage spectrum consists of a constant component and a number of high-frequency harmonics. However, the amplitude of the latter is small compared to the maximum required voltage on the load (11), which ensures the best conditions for the operation of the Low-Pass Filter.

A power digital-to-analog converter containing an automatic control system closed in voltage compensates for the compensations from both the power sources and the load side, thereby ensuring the stabilization of the average value of the output voltage with the accuracy of the least significant bit.

Claims (1)

Claim A power digital-to-analog converter containing a computing device, a "code-pulse-pulse-modulated signal" converter with two inputs and two outputs, which drives a pulse generator; connected to one of the converter inputs of a "code-pulse-modulated signal" trigger with two separate inputs, a power reversing converter and a comparator device, which is due to the fact that, in order to increase the stability of the output voltage, to reduce power losses for switching to power Transducer elements and additional power losses in the load, the code-voltage measuring converter, sawtooth generator, threshold device and low-pass filter are introduced into it, p When in use, transducer "code-voltage" output coupled to the first input of the comparator, a second input coupled through a low pass filter with the output of the power converter and the reverse output through an amplifier and a regulator to a first input porogo ^ l · 760437 device, the second input of which is connected via a sawtooth generator to the first output of a code-pulse width modulated signal converter, the second output connected to the first trigger input, the second input of which is connected to the output of the threshold device, the first output of the computing device containing higher bits of the binary code, connected to the first input of the SILOV transducer and to the first Input of the code-voltage transducer, the second output of the computing device remains GOVERNMENTAL L LSBs un-coupled to the second input of the measuring Vh. X0 & 01001 01000 00111 00110 00101 00100 00010 00001 P-1 fi. " one about P * 3 about R*' about P-0 the converter and the first input of the code-width-pulse-modulated signal converter, the second input of which is connected to the output of the master oscillator, and the third output of the computing device serving sign bit code connected to the second input of the power Converter, the third input of which is connected to the output of the above-mentioned trigger.