Design of a switching power supply for single-phase and three-phase power supplies
Selection of PWM Circuit
The article selects the UC3846 dual output current type PWM controller IC. This circuit has a *maximum* duty cycle of 50% at a switching frequency of 20KHZ, so its control is effective and stable.
IGBT drive and protection
IGBT work is controlled by the positive and negative gate voltage, when UGE>0, IGBT on, when UGE<0, (general UGS ≤ -5V), IGBT cut-off. Taking into account its characteristics and operating principle, the choice of positive and negative dual power supply M57962L-type special drive integrated circuit. The circuit has a built-in timing logic short-circuit protection circuit, and has a protection delay function. Driver protection principle circuit shown in Figure 3 (b). In addition to the IGBT drive circuit itself to provide short-circuit (overcurrent) protection, in parallel with the IGBT RC buffer branch and power supply parallel absorption capacitors on both sides of the method is also effective.
Conclusion
This switching power supply is more suitable for practical applications. Because the parameter design of the rectifier circuit is based on single-phase considerations, when used in three-phase power supply has sufficient margin, so that the system is more stable and reliable; used in single-phase power supply can also work normally. This solves the contradiction of switching power supply due to power supply limitations. With this method, the existing switching power supply can also be transformed into a single-phase, three-phase switching power supply can be supplied.
