4 diode in configuration of use bridge-type commutator are what undertake rectification to AC voltage is the simplest, also be the grooviest method. A diode moves to be able to be complete bridge commutator and car provide a simple, be to one’s profit with the alternator in commutator of a bridge-type and the solution of electric current of 0 static states.

 

Nevertheless, although diode is had to losing voltage normally the fastest answer speed, but because their meeting is losing a knot to falling to voltage pressing (of Vf ~0.7V) cause higher power loss consequently formerly. These power loss can be caused calorific, need designs personnel to execute radiating tube put in order, increase size of systematic cost and solution thereby. The another defect of diode is taller divulge voltaic — reversely highest meeting is achieved about 1mA.

 

It is OK to replace high loss diode with MOSFET of N raceway groove through removing diode commutate parts of an apparatus or appliance to pressure fall to reduce power loss considerably. MOSFET of N raceway groove has small RDSON, and they are pressed relevantly falling also is the smallest.

 

Express 1 in it is commutator of diode of a 5A (I_rms = 3.5A) and a 10mΩ between the rectification parts of an apparatus that is based on MOSFET quite.

 

Express 1: MOSFET and diode power loss are compared

 

Apparent, when use MOSFET, power loss is small to your person fab, and design personnel also need not be used costly and cumbersome carbon fin has heat government. However, everything all has price. MOSFET of N raceway groove needs drive of a grid to come electric current from the source extremely conduct to leakage extremely, and need turns into in AC sine wave close quickly when negative worth. Through combining controller of commutate of MOSFET of N raceway groove and diode of 4 LM74670-Q1 intelligence together, MOSFET grid can be shut inside the negative cycle in sine wave. LM74670-Q1 design is used at alone drive MOSFET of each N raceway groove, so that emulate,one is done not have to the ideal diode that conducts loss. LM74670-Q1 attacks with develop of an in suspension and charge pump realizes true diode to replace.

 

Graph 1 those who show is to be in design of commutator of bridge-type of a Quan Bo the LM74670-Q1 that move.

 

Graph 1: Commutator of bridge-type of LM74670-Q1 intelligence diode moves

 

In method of this bridge-type commutator, every diode is replaced by LM74670-Q1 solution place, this solution includes integrated circuit MOSFET and capacitor of pump of a charge. Every solution moves independently, and input weaveform to AC like diode make answer. LM74670-Q1 brings a foot to feel continuously with positive pole and cathode the voltage that measures MOSFET to go up, and come according to voltage polarity be opened and shut MOSFET grid. In AC weaveform inside cycle, if pursue 2 in be shown, MOSFET M1 and M3 are electric, and the grid that is aimed at M2 and M4 is closed by corresponding LM74670-Q1.

 

Graph 2: AC is inputted inside cycle to conduct

 

When be worth to lose when AC wave deformation, it is with the LM74670-Q1 of M1 and M3 photograph correspondence inside the time of 2μs answer to losing voltage to make, and close break the grid of two MOSFET. Inside this time, if the graph is shown 3 times, m2 and M4 MOSFET put through.

 

Graph 3: Inside AC input negative cycle to conduct

 

The MOSFET that uses in this application must have to be less than the bar source voltage that is equal to 3V (VGS) threshold values, and low grid capacitance. The electric parameter with important another is the voltage on MOSFET body diode, this value must be 0.48V left and right sides when low output electric current. Heart state apparatus (MOSFET of power of raceway groove of TI) 60V CSD18532KCS N or other NexFET™MOSFET is the optimal choice of this application.

 

Pursue 4 those who show is one is aimed at the oscillograph graph that is based on the LM74670-Q1, intelligent bridge-type commutator that has 4 CSD18532KCS MOSFET. This commutator inputs power source power supply to move by the AC of a 12V 60Hz, the output of commutate of a classics generates in this give typical examples. What show in the light of the VGS of MOSFET M1 is LM74670-Q1 to shedding classics MOSFET controlling fashion to what conduct, and how to come through closing grid block breaks retrorse tension.

 

 

Graph 4: Commutate of classics of LM74670-Q1 intelligence bridge-type is outputted

 

Graph 5 compared commutator of LM74670-Q1 intelligence bridge-type (configuration has MOSFET of raceway groove of 4 CSD18532KCS N) (Zun Tu) as low as a convention to pressure fall diode (commutator of Vf = 0.5V) (right graph) the hot property between. Two designs move in tall electric current (below 10A) , and did not heat up management and empty throughput. The temperature of every diode in commutator of a diode is achieved about 71°C, and the temperature that the CSD18532KCS MOSFET in LM74670-Q1 commutator is running a condition to fall likewise is 31°C about.

 

Graph 5: With the hot property of groovy diode commutator is compared

 

Anyhow, design of complete bridge commutator has the intelligent diode that is based on LM74670-Q1 the following these characteristics and advantage:

 

● improved systematic efficiency about 10 times.

 

● MOSFET need not any heat government that use in the light of tall electric current.

 

This design reduced ● systematic cost, and reduced printed circuit board the space that go up.

 

● support is as high as the taller frequency of 400Hz, and the AC voltage n that is as high as 45V, what this makes its become a car to use alternator application is appropriate replace parts of an apparatus.