Working principle of asemi three-phase rectifier bridge

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The circuit composed of six rectifier diodes is called three-phase rectifier bridge circuit . Mention the appearance of three-phase rectifier bridge , Because of the increase of power and requirements .

In understanding ASEMI Before the working principle of three-phase rectifier bridge , First of all, we should know how the three-phase rectifier bridge is composed . As shown in the figure below , Three phase rectifier bridge 6 Rectifier diode , The characteristics of the diode ： The positive potential is higher than the negative potential , Then the diode is on ; When the positive potential is lower than the negative potential , Diode cut off .

 

It is not difficult to see from the wiring diagram , The characteristics of this circuit are ： At any time , The rectified current flows from the diode connected to the highest phase of the three-phase electricity , The lowest potential passes through the load R Flow to the other phase diode to the power supply . The waveform diagram of this process is roughly shown in the following figure .

 

In the figure ： When ωt=0,Ua=0,Ub= - √3/2•Um,Uc= +√3/2•Um when , At this time, the current will be connected Uc flow DC1 diode , Then flow through the load R, Slave load R Retrogression Ub. When the temperature is higher than 0 And less than 30° when ,Uc Has the highest potential ,Ub Has the lowest potential , So in this temperature time ,DC1 and DB2 The two diodes are on .

When the temperature is higher than 30° And below 90° when ,Ua Has the highest potential ,Ub Has the lowest potential , So at this temperature time point , Two diodes DA1 and DB2 Conduction .

If the temperature is 90° and 150° Between ,Ua Has the highest potential ,Uc Has the lowest potential . As you can see from the diagram , During this temperature period , Two diodes DA1 and DC2 They are all conductive .

In the above three cases, the diode is always on , That is, from beginning to end , The diode is always on , That is, whenever , Of the three diodes in the circuit , The highest positive potential turns on , Then from the resistance R Return to the corresponding power supply through the diode with the lowest negative potential among the following three diodes .

It's not hard to find out , In this circuit , At least two diodes are connected in series with each other . The current is the same as the load current , But the load current is continuous , The diodes are divided into three groups to conduct circularly , therefore , If the diode current is to be selected, it is one third of the load current . That's all ASEMI Working principle of three-phase rectifier bridge .