9 » IC Electronic information » Category: M

IC Electronic information

Microcontrollers DC power control panel design

In Electronic Infomation Category: M | on April 19,2011

Abstract: A single chip control thyristor trigger pulse to the core of the DC power control panel system, which implements the synchronization of thyristor triggering pulse signal generation, phase shift, drive and EPF6016TI144-2 datasheet and system over-voltage / Over flow protection. Users can set the keyboard to the output DC power supply, eight out digital display the actual output voltage / current; in with the design of hardware and EPF6016TI144-2 price and software, the system realizes intelligent three-phase alternating current to determine the phase sequence, the synchronization pulse formation, break detection, pulse-code calculation, the output data sampling, soft-start control and EPF6016TI144-2 suppliers and proportional control functions.

0 Introduction

Microcontrollers DC power control panel, including A / D acquisition and conversion, measurement, display, synchronization, automatic phase sequence determination, phase trigger, over current / voltage protection, phase loss detection part, and rectifier transformers, batteries , meters and other components together constitute the complete sets of equipment. Equipped with a charging, constant current, voltage regulators, and other work, for power plants, substations, hospitals, factories, and other departments as a control, DC power operation or lighting. Microcontrollers power control circuit is simple and clear system hardware, high accuracy digital trigger pulse, the system regulating speed, high performance and reliability.

1 System Architecture

1. 1 rectifier transformers and main circuit

Rectifier transformer and the main circuit of the circuit shown in Figure 1. Multi processor control system for DC power converter main circuit is fully controlled three-phase bridge rectifier, rectifier transformer primary side control and protection devices are relays, control switches, fuses, power light and so on, one side of the 380 V AC power connection . Transformer secondary side as a fully controlled three-phase bridge rectifier power supply, the main circuit in six of the thyristor, the thyristor circuit trigger pulse circuit must meet the following conditions:

Figure 1, the main transformer and rectifier circuit

(1) trigger pulse must be synchronized with the main circuit power and the scope of a certain phase shift; (2) there should be a trigger pulse width to ensure reliable triggering of the thyristor conduction; (3) trigger pulse steep leading edge as far as possible and have enough power.

1. 2 power control board hardware diagram

DC power control panel by the four 51 series, namely GMS97C52, GMS97C51 and two AT89C2051.

GMS97 series of microcontrollers produced by the South Korean LG, and TntelMCS 51 series microcontroller compatible, and has low power consumption, cheap, OT P (One Time Pro grammable) and so on. Power control board hardware block diagram shown in Figure 2.

hardware block diagram of Figure 2, the power control board

Following four MCU Features:

(1) U18 ((AT89C2051) for receiving AC voltage, forming rectangular sync pulse, to send forward the phase-shifting pulse U 20; also used to determine phase sequence to detect disconnection function.

(2) U20 (GMS97C52) for A / D acquisition test, the measurements will be collected after the digital filter setting value comparison, the amount of deviation to modify the control so as to achieve the purpose of adjusting current and voltage. While the input value human contact, modify the voltage and current setting value stored in the E2 PROM, display parameters and fault information.

(3) U19 (GMS97C51) is for the use of remote control or a group, receive and transmit remote control information to the U20 (GMS97C52), while processing the alarm information entered by the U20.

(4) U23 (A T89C2051), receives the phase shifted pulse, adjust the width of the narrow pulse output trigger thyristor pairs.

2 Hardware Design

2. 1 sync pulse forming circuit

In the three-phase bridge full-controlled rectifier circuit, the control angle is the corresponding line voltage zero crossing, from the full-controlled bridge rectifier circuit 4 #, 6 #, 2 # K thyristor three-phase terminal phase were obtained abc voltage access circuit K2 c, K6 b, K4 a terminal, shown in Figure 3. The circuit access to the two-phase voltage optocoupler U 32, U32 4-pin negative output signal of the phase transition time is the turn-on thyristor trigger the earliest moment, that is, in this moment, with the interruption, in order to achieve synchronization. In addition, because the three-phase power phase difference of 120, can be analyzed, regardless of the order of power line access to, the phase sequence between the positive sequence and negative sequence only two, the software can be issued for their further identification and the corresponding right six-way trigger pulse signal.

2. 2 Driver

Figure 4 circuit RV6, R V12, C + 12 diversion effect to trigger circuit can improve anti-interference ability, U 6 transistor amplifier for the output stage of the trigger pulse from the microcontroller power amplifier, T8 is the pulse transformer , L7 indicates thyristor work, CF6 and RL7 thyristor interference can improve the ability to reduce the gate input impedance.

Figure 3 sync pulse forming circuit diagram

Figure 4, the control unit and the trigger pulse circuit

2. 3 current and voltage sampling circuit

Circuit in Figure 5, A / D converter of choice is 12-bit successive approximation TI, chip T LC2543, sample and hold it with the serial three-state output function, in the instrumentation in the wider application. The application of current sampling circuit RMS converter chip AD736, simplify the software design. The main circuit output current and voltage signals by the A / D converted into the microcontroller U20, SCM change control according to the amount of deviation and the achievement of over-voltage current protection, fault diagnosis functions.

Figure 5, current and voltage sampling circuit

2. 4 watchdog circuit

Control board is set up with the watchdog timer control circuit, which uses MAX813L chip, shown in Figure 6. Control circuit, if the 1. 6 s is not detected within their work, it will continue to send the reset signal until the program back to normal.

3 Software Design

watchdog circuit in Figure 6

3. 1 synchronized with the implementation

First voltage signal based on three-phase synchronous interrupt signal provided to the MCU, the MCU after the interrupt response, according to three-phase full-controlled bridge rectifier circuit of the trigger pulse to the requirements of the trigger pulse. When the a, b phase commutation point, as shown in Figure 3 (a) below, a phase b phase comparison between the phase voltage signal to generate a falling edge of the microcontroller U 18 1 external interrupt pins ( INT1), through the interrupt event generates a sync pulse, sync pulse sent to U 20 (AT 89C52), the waveform diagram shown in Figure 7.

sync pulse waveform in Figure 7

3. 2 trigger pulse phase and pulse width control

The system is by changing the microcontroller chip timer / counter counts to change the firing angle, thereby changing the DC voltage and DC current.

U18 generated sync pulse to the microcontroller U 20 microcontroller, U20 SCM measurements by comparison with the setting value, the ratio adjustment, so setting the value equal to the measured values, while generating phase pulses to the U 23 of the external interrupt 1 ( INT1), after the response to external interrupt 1, P1 output port to start the first encoder pulse, and timing, corresponding to a code issued for each 60 pulse encoder pulse has been sent to the last completed, and then return to wait for external interrupt 1 (INT1) of the next interrupt request, that upper layer sends the sync pulse to the phase shift microcontroller U23. Pulse code double pulse coding used to achieve double-pulse triggering. In this process, T0 used for the counter, counting at least N times the hair trigger pulse. N is calculated as follows:

Known: power frequency f = 50 Hz, the crystal frequency F = 8 MHz, timed for the 60 , then:

According to N values, and timer / counter mode, you can calculate the timer / counter initial value.

3. 3 ratio control adjustment program

To make the output voltage / current value and setting value match, the software control, the control volume is proportional to the setting value and the deviation between the measured value, so continue to follow the actual output value of the setting value, and ultimately reach consensus. In addition, the subroutine, the system starts, within the 5 s, regulating the amount of subroutine only allows control of a unit step, step increases, which prevents the voltage rising too fast, in order to achieve soft-start.

Control the amount proportional to the measured values ??and setting the deviation, in theory, PID algorithm used to regulate the expression of the discrete difference equation as follows:

Where: en, en-1, en-2, respectively, for the first n times, n - 1 st and n - 2 times the voltage deviation; KP, TI, TD are the proportional coefficient, integral coefficient and differential coefficient , T for the introduction of cycle.

4 Concluding Remarks

The DC power control panel with the following in the design of several prominent features:

(1) using the interrupt function: four 51 series, each piece has four interrupt sources, such as synchronization, phase, phase sequence and phase loss signal discrimination are used to pass interrupt function, thereby significantly improving the system response speed and reliability.

(2) A / D resolution is 12 bits, the minimum count of the timer interval is 1. 5 s, the small disturbance voltage and current accuracy of up to 5?.

(3) automatic identification with the power phase sequence, phase auto-detection, fault alarm and status display.

(4) multi-MCU design, the microcontroller features a single, adjustable speed and improve the reliability of system performance.

EPF6016TI144-2 datasheetEPF6016TI144-2 suppliersEPF6016TI144-2 Price

All right © 2010-2016 Certificate