Advantages of push-pull switching power supply
Rectifier output push-pull transformer transformer switch switch supplier power supply supplier, because the two switch tubes work alternately, it is equivalent to two switching power supply and switching power supply suppliers output power at the same time, and its output power is about twice the output power of a single switching power supply. The two switching devices of the push-pull switching power supply have a common ground terminal. Compared with the half-bridge or full-bridge switching power supply, the driving circuit is much simpler.
working principle
The rectified output push-pull transformer switching power supply, because the two switching tubes work alternately, is equivalent to the output power of two switching power supplies at the same time, and its output power is about twice that of a single switching power supply. Therefore, the push-pull transformer switching power supply has a large output power and high working efficiency. After bridge rectification or full-wave rectification, only a small filter inductance and capacitance are needed, and the output voltage ripple can be very small.
In the push-pull circuit, the two switches S1 and S2 are turned on alternately, and AC voltages with opposite phases are formed at both ends of the windings N1 and N’1 respectively, and the output voltage can be changed by changing the duty cycle. When S1 is turned on, the diode VD1 is in the on-state, and the current of the inductor L rises gradually. When S2 is turned on, the diode VD2 is in the on-state, and the current of the inductor L gradually rises. When both switches are off, both VD1 and VD2 are on, each sharing half of the current. The peak voltages that S1 and S2 bear when they are off-state are both 2 times Ui. S1 and S2 are turned on at the same time, which is equivalent to a short circuit of the primary side winding of the transformer, so the two switches should be avoided to be turned on at the same time. The duty cycle of each switch cannot exceed 50%, and there must be a dead zone.
Since the two control switches K1 and K2 in the push-pull transformer switching power supply work alternately, the output voltage waveform is very symmetrical, and the switching power supply provides power output to the load during the entire working cycle, so the instantaneous response speed of the output current is very high, and the voltage output characteristics are very good. The push-pull transformer switching power supply is the switching power supply with the highest voltage utilization rate among all switching power supplies. It can still maintain a large power output when the input voltage is very low, so the push-pull transformer switching power supply is widely used in DC/AC inverters or DC/DC converter circuits with low input voltage.
After the push-pull switching power supply is bridge rectified or full-wave rectified, the voltage ripple coefficient Sv and current ripple coefficient Si of the output voltage are very small, and only a small energy storage filter capacitor or energy storage filter inductor is needed to obtain an output voltage with small voltage ripple and current ripple. Therefore, the push-pull switching power supply is a switching power supply with very good output voltage characteristics.
In addition, the transformer of the push-pull switching power supply belongs to bipolar magnetic polarization, and the magnetic induction range is more than twice that of the unipolar magnetic polarization, and the transformer core does not need to leave an air gap. Therefore, the magnetic permeability of the push-pull switching power supply transformer core is many times higher than that of the unipolar magnetic polarization forward or reverse switching power supply transformer core; thus, the number of primary and secondary coil turns of the push-pull switching power supply transformer can be more than twice that of the primary and secondary coil turns of the unipolar magnetic polarization transformer. Therefore, the leakage inductance and copper resistance loss of the push-pull switching power supply transformer are much smaller than those of the unipolar magnetic polarization transformer, and the working efficiency of the switching power supply is very high.
In the push-pull switching conversion circuit, the energy conversion is controlled alternately by two tubes. When the output power is the same, the current is only half of the single-ended switching power tube, so the switching loss is reduced and the efficiency is improved.
advantage
1. The output current transient response speed of the push-pull switching power supply is very high, and the voltage output characteristics are very good. Push-pull switching power supply is the switching power supply with the highest voltage utilization rate among all switching power supplies.
Since the two control switches in the push-pull switching power supply work alternately, the output voltage waveform is very symmetrical, and the switching power supply provides power output to the load within the entire cycle, so the output current transient response speed is very high, and the voltage output characteristics are very good. Push-pull switching power supply is the switching power supply with the highest voltage utilization rate among all switching power supplies. It can still maintain a large output power when the input voltage is very low, so the push-pull switching power supply is widely used in low input voltage DC/AC inverters and DC/DC converter circuits.
2. The push-pull switching power supply is a switching power supply with good output voltage characteristics.
After the push-pull switching power supply is bridge rectified or full-wave rectified, its output voltage ripple coefficient and current ripple coefficient are very small. Therefore, a small energy storage filter capacitor or energy storage filter inductor is needed to obtain an output voltage with very small voltage ripple and current ripple. Therefore, the push-pull switching power supply is a switching power supply with good output voltage characteristics.
3. The leakage inductance and copper resistance loss of the push-pull switching power supply transformer are much smaller than those of the unipolar magnetized pole transformer, and the working efficiency of the switching power supply is high.
The transformer of the push-pull switching power supply belongs to the bipolar magnetization pole, and the magnetic induction transformation range is more than twice that of the unipolar magnetization pole, and the transformer core does not need an air gap. Therefore, the magnetic permeability of the push-pull switching power supply transformer core is many times higher than that of the forward or flyback switching power supply transformer core with unipolar magnetization poles. In this way, the number of turns of the primary and secondary coils of the push-pull switching power supply transformer can be more than double the number of turns of the primary and secondary coils of the unipolar magnetization pole transformer. Therefore, the leakage inductance and copper resistance loss of the push-pull switching power supply transformer are much smaller than those of the unipolar magnetized pole transformer, so the working efficiency of the switching power supply is higher.
4. The driving circuit of the push-pull switching power supply is simple.
The two switching devices of the push-pull switching power supply have a common ground terminal. Compared with the half-bridge or full-bridge switching power supply, the driving circuit is much simpler.
5. The push-pull switching power supply does not have the possibility of simultaneous collusion of two control switches like the half-bridge and full-bridge switching power supplies.
