Step-up step-down type output voltage balancing circuit

The invention provides a step-up step-down type output voltage balancing circuit and a control method thereof. The step-up step-down type output voltage balancing circuit is characterized in that the circuit comprises an input direct-current voltage source Uin, a step-down circuit and step-up balanced bridge circuit, and the circuit can be controlled through an output voltage controller, an output voltage balancing controller and a PWM generator. The purpose of step-up step-down is achieved, a neutral line is arranged at the output end of the circuit to achieve output voltage balance, an input direct-current voltage changing in a large range is converted into a constant output direct-current voltage, the output direct-current voltage is converted to two direct-current voltages with equal value and opposite polarity through the neutral line, so that the problem of electrolytic capacitor series connection and voltage sharing is solved, and requirements for input voltage balance of a converter or for different input voltages of post-electric-equipment are met.