Laboratory_03_for_AC-DC_Converter[1]

Complete the experiment of three-phase Thyristor controllable converter operating in two-quadrant by oneself
Purpose：
Know the true circuits and connections, observe and analyse the Key waveforms of the circuit
uab uac ubc uba uca ucb
3、已知该vd波形中最高电
压为500V，求此时输出电 压平均值Vd。
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0
t ω
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Solution 1 1、 T3管损坏
0
ud
uab uac ubc uba uca ucb
ωt
2、α=30º 3、
4 500 Ud 2.34 cos30o 275.81V 6 3 2
A
C
B
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Solution
② 测相控角α并将它调整到38º 假设已测得的A、B、C三相相序为A超前B，B超前C 由于线电压UAB（或UBC或UCA）的正向过零点（从负半周进 入到正半周的过零点）与T6管（或T2管或T4管）的自然换相 点为同一时刻，并且线电压UAB（或UBC或UCA）与T6管（或 T2管或T4管）的触发信号有公共点，因此可用两个探头同时 测线电压UAB（或UBC或UCA）和T6管（或T2管或T4管）的触 发信号得α角，并将它调整到38º 27
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Fig 1. CA6100 Board
Control part
Driving part
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Output ports
Six pulse transformers
Power supply
LSI
Power transformer
Controler of α
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One important feature of CA6100 is that a phase-lockloop (PLL) is ability to provide the synchronous triggering signal with AC input voltage for SCR, instead of a synchronous transformer. The principle of triggering signal is seen in Figure 2.
4. Adjust the voltage of second side in three-phase transformer below 80 V, then turn the controller of α respectively in 60ºand 90º observe and draw the , waveforms of vd, Id, vT and triggering signal;
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Solution
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Solution
③ 测ud 的波形 保持α=38º，用一个探头测直流输出母线电压ud 的波形（注 意极性）。 ④ 测id 的波形 保持α=38º，用一个探头测电阻箱两端电压的id波形（注意极 性）
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Understand the request of triggering signal for three-phase Thyristor Full-bridge controllable converter See the attached《CA6100可控硅触发电路》
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Content：
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1 Prepare this experiment
Draw the topology of three-phase Thyristor Fullbridge controllable converter Summarize the basic principle of three-phase Thyristor Full-bridge controllable converter when it operates in two-quadrant
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Example 2 一实验电路如图所示。负载为大电感和电阻 箱，晶闸管触发脉冲为单脉冲。假设A、B、C三相电 压平衡，但相序未知，相控角α可以调节。要求用双踪 示波器测量相控角α= 38º时的直流输出电压ud 、输出 电流id 的波形，试说明实验步骤。
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Laboratory 3. Three-phase Thyristor Converter 负责教师：陈洛忠 This experiment will begin from 2011-5-2 For the three-phase Thyristor Full-bridge circuit can operate two-quadrant, i.e. rectifier mode and inverter mode, converter is called in this experiment, instead of rectifier
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Figure 2. principle of triggering signal
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Two types of triggering signal can be provided in the first side of every pulse transformer in CA6100, which can be seen in Figure 3. The double 30ºof them is used in this experiment.
Figure 3. Wave of Triggering signal in the primary side of A phase pulse transformer
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Role ？
The insulated and strong triggering signal for each SCR can be given through the driving circuit seen in Figure 4.
6. Turn off the utility power and Adjust the voltage of transformers to zero after the teacher admits.
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3 Problems 1. How dose ac side inductance effect on the current communicating in this converter circuit? 2. How can this Thyristor controllable converter operate in inverter mode? Try to analyse the reasons.
3. If one of the thyristors in the converter is fault, how can you choose new one to replace that destroyed one ?
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Example 1 三相全控桥整流电路接阻感负载，Ld=∞，直流 侧电流连续，正常工作时突然有一个晶闸管烧断，出现如 下图vd波形。试回答下列问题： 1、判断T1-T6中的哪一个管子损坏？（注T1、T3、T5分别对 应a、b、c三相的上桥臂；T4、T6、T2分别对应a、b、c三 相的下桥臂） ud 2、大致判断相控角α=？
Figure 4. Driving circuit for A phase
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Figure 5. Wave of Triggering signal in the second side of A phase pulse transformer
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2 Steps of the experiment 1. Check the all equipments and connections in the circuit; 2. Adjust the single-phase transformer to zero voltage; 3. turn on the utility power, the three LED in CA6100 light;
Request：
Step by step safely Do it by oneself Draw carefully waveforms Analyse rightly conclusion
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Introduction of the experiment circuit
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DC output
K
G A
AC input
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Triggering and driving circuit
A general control circuit board named CA6100, which is composed of Large Scale Integration (LSI) is used in this experiment. The CA6100 is seen in Figure 1.
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Solution 2 测ud 、id的波形 ① 确定A、B、C相序： 用双踪示波器测自耦调压器三根输出线之间的电压波形即可： 设某相位C相，以此相位公共点测两个线电压vxc、vyc，则相 位超前的是vAC，相位滞后的是vBC。 （注意：示波器探头的接法，两个探头的地接在一起或只接一 个探头的地而另一个探头的地悬空）。