Three main circuit design

Rectifier transformer design. Through the transformer secondary side voltage U2 calculation, a, secondary phase current I1, I2 calculation and transformer capacity calculation final rectifier transformer model. Thyristor element choice. After computing thyristor rated voltage and rated current of the brake tube to determine the thyristor model. The protection of dc speed regulating system. Thyristor have commutation is convenient, the advantages of no noise. Design thyristor circuit in addition to the right choice thyristor rated voltage, rated current parameters outside, still have to take the necessary over-voltage [3], over current protection measures. The right protection is thyristor device can reliably normal operation of the key.
To rotating joints over-voltage protection part to points, good communication turned half around voltage protection, dc turned half around voltage protection and device on both ends of the over-voltage protection three. In the current protection, fast fuse cut-out time short, protection performance is good, is the application of the most common protective measures. Fast fuse can be installed in dc side, ac side and directly with thyristor series. In order to make the dc load get smooth dc current, usually in the rectifier output circuit string into with the gap core reactor. 4 control circuit design 4.1 single-chip microcomputer system For the rapidity and control accuracy requirement is high speed control system, can choose high performance 8-bit microcontroller, the system USES the Inter of MCS - 51 single chip microcomputer 80 c31 microcomputer in [5]. SCM system, 80 c31 microcomputer external 27128 eprom as 16 k program memory, deposit all control software. Use two pieces of 74 ls374 and four in the PNP power triode to dynamic scanning system drive four LED digital to rotary union display speed, setting speed, electric current and so on data, two pieces of 74 ls374 using line selection method and 80 c31 microcomputer interface, address respectively 0 DFFFH and 0 BFFFH. In 80 c31 microcomputer mouth of P3 in external three key, a start/stop button, used to start or stop the motor running; The other two to show option key, a used to control display speed setting value, and the other one for control and display current value, not to the two key, show the actual motor speed.
Another use a piece of 74 ls374 redundant output line, external two LED luminous tube, one for display working properly or not, it every 1 second shining one time. The other one for display is in the running state. 4.2 current measurement and speed given value input Systems use ADC0808A/D converter. Write the address, start A/D converter. A/D transformation completed, produce EOC pulse and interrupt. At this time, MCU can be read in conversion results. Ac current through the current transformer into 0 ~ 5 v voltage signal, the rectifier and filter added to fiber optic rotary joint the ADC0808 on IN0. Speed given using potentiometer input, it added to the IN1. After adjusting speed given value, can press speed given shows that key. At this time, the four general LED display corresponding to the potentiometer input speed given value, can adjust potentiometer to display value for the given value.