The push-pull converter is one of the oldest switching topologies and it can give multiple outputs with single input.

Output voltages can be higher or lower than input voltages when changing the winding’s turns ratio of the transformer.

Push-pull Converters distinguishing feature pairs of transistors in a symmetrical push-pull circuit, transistors periodically reverse the current in the transformers by switching on and off units. Therefore, current is drawn from the line during both halves of the switching time. With a single transistor working in the same way, but current is drawn half the time, that is difference between buck-boost converters and push-pull converter. So with this push-pull circuit, push–pull converters have steady input current, create less noise on the input line, and are more efficient in higher power applications.

PSIM:Push-Pull Converter. Aiming at the problem of switching power supply stable output, a push-pull switching power supply was designed. The switching frequency is 100kHZ and the output voltage is 5V. System model of the push-pull switching power supply is established on PSpice, and research on the output performance of the push-pull switching power supply. By the parameter sweep analysis of load, the push-pull. A simple push-pull DC/DC converter with a fixed 50% duty cycle is often used as a low noise transformer driver in communication systems, medical instruments and distributed power supplies. This simple scheme provides no voltage regulation—requiring a low dropout (LDO) post regulator—a combination that presents potentially serious problems.

Fig. 1: Typical Push-pull converter Circuit DiagramA typical push-pull converter contains:

• 2 transistors as switches (Q1 and Q2)
• 1 transformer with center tapped (Np1, Np2, Ns1 and Ns2)
• 2 diodes as passive switches/rectifiers (D1 and D2)
• 1 LC filter (CO and L1)
• 1 input capacitor (C1)

Fig. 2: Current Flow w/ Q2 Switches ClosedAt first half cycle of switching frequency, Supply is given at Vin, Q1 is on and Q2 is off, direction of current is clockwise, Np1 gets charged, Ns1 and Ns2 also will get charged due to induction. D1 will get forward biased and D2 will be reverse biased. LC filter will smooth the output voltage and ripple to a more pure DC form output voltage.
Fig. 3: Current Flow w/ Q1 Switches ClosedAt second half cycle of switching frequency, Q1 is off and Q2 is on, direction of current become counterclockwise, Np2 gets charged, Ns1 and Ns2 will keep inducing. But direction of current will be reversed, D1 will get reverse biased and D2 will get forward biased. LC filter will carry the filtering function as mentioned above.

Two transistors Q1 and Q2 keep on and off periodically and repeatedly in every period so we can get steady and regulated output voltage. However, the most important is that two transistors must never be closed simultaneously, they will damage if they get closed together.

Push-pull designs are popularly used in middle to high power applications (150W to 1000W), operating with greater efficiency and less noise. Many diverse applications for these products include:

• Power Supplies
• DC to AC inverter
• DC to DC converter
• Equipment
• Other applications

MPS has extensive experience designing and supplying push-pull transformers to automotive, medical, military and industrial markets with excellent customer satisfaction. Please contact MPS Sales for any of your magnetic component requirements.

To view our push pull transformers catalog, click here.

Pete Millett's DIY Audio pages

For technical books, tube data, vintage data, transformer data, and McIntosh data, go to:www.tubebooks.org

Last update: 3/9/21 - Posted a 4D32 SE UL amp

4/9/19 - Added a Nutube balanced (differential) amp for headpohone or line amp use

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Audio projects and experiments:

Power amps

The 'NuclassD' 50W class-D hybrid amp using the nutube

A hybrid (SS driver) class A2 DHT amp

A 50 watt monoblock version of the 'Engineer's Amp'

A PL177 single-ended amplifier

'La Luxuriante' stereo R120 SE amp

'Fatboy', a low-distortion zero-feedback push-pull 300B amp

A compactron triple-triode driver for push-pull amps

'Mr. Potatohead' 815 amp - 50W from 2 tubes in class AB2

The '807' Push-Pull amp using driver boards below

Push-pull driver PCB, a (nearly) universal driver for push-pull amps

Download

Push Pull Converter Pspice Student