HI, can anybody please suggest me schematic circuit diagram of three-phase sine wave generator.?

Question

HI, can anybody please suggest me schematic circuit diagram of three-phase sine wave generator using discrete components only ( 0', 120', 240' )..TQ

Answer 1

The only good way to do that is digitally with a wave table. But you could use the same strategy that you need for any analog sine wave generator, ie Automatic gain control. You can use amplitude to automatically set a phase shift to 120° since they are related. The third phase is just the inverted sum of the other two. If you just needed one frequency then it's simple to set a static phase shift and amplitude. A lot depends on your requirements. It's not difficult to make a 4 bit wave table if a 16 step sine wave is OK. The beauty of a wave table is that it has no settling time like analog methods.

http://en.wikipedia.org/wiki/Variable-frequency_drive

Answer 2

Do not need a circuit diagram. It is a very simple device contains three coils with the same amount of turns. More turns produce higher voltage. Thicker wire size generates higher current. Pack these three coils into 360 degree drum. Each coil with iron core takes about 120 degree. Obtain a cylinder shape magnet just fit inside the drum. Let it rotates and three phase power source comes out from three coils terminals .

Answer 3

If you are in need of a 3-phase signal generator as opposed to a 3-phase power generator. The following is a description of a process that uses simple digital circuitry and resistor networks. (I have used this method to generate a variety of frequency synthesized sine/cosine signal generators.)

This process requires two CMOS 8-stage serial in/parallel out shift register chips (e.g. SN74HC595) connected in tandem to produce a 16 stage parallel output shift register. The input to the first shift register must be a symmetrical square wave at the frequency of interest. The shift register chips must be clocked at 12X of the needed output frequency. (These two square waves could be most easily obtained from a clock generator whose output is the 12X frequency, and then dividing the clock by 12 to obtain the desired frequency.) The square wave output of each shift register represents a 30 degree segment of the output frequency.

A reasonable approximation to a sine will be produced by a set of resistors that are attached to five consecutive SR outputs. The conductance of these resistors must be related to a sine function as per the table below:



SR output no.___ sine(N/12*Pi)_______Suggested 1% resistor values

1 _____________ 0.500___________ 20K

2_____________ 0.866____________11.5K (nearest value)

3_____________1.000_____________10K

4______________0.866 ___________11.5K

5 _____________0.500 ____________20K

6 _____________ 0.00_____________ (no resistor)



The set of resistors should all be connected together as a summing node. The voltage output at this node will appear as a stepped sign wave whose amplitude ranges from 0 to +5 V. one cycle of the output signal is represented by 12 time segments and six amplitude levels.

The signal’s main harmonic component is at the clocking frequency (12F), and can be reasonably well filtered by using a grounded capacitor at the resistor node (the node resistance for the values given is 2.59K.) The R-C’s cut-off frequency should be set near to or above the desired output frequency, and the capacitor should be precision to prevent phase shift variation that could occur from one generator output to the next. The node’s output should be capacitively coupled to an appropriate buffer amplifier. (If a relatively pure sine wave is required, a third-order Butterworth active filter whose cut-off frequency is somewhat above F would be a good choice.)

The 120 degree output signal would be similarly produced by connecting the same resistor network to SR outputs 5 through 10, and the 240 degree output signal produced by connecting to SR outputs 9 through 14.

Answer 4

It depends on how much power you need and how accurate the phase angle has to be.