Resonant Push-Pull Converter Control for Zero-Loss Switching
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Solution Overview
Problem
Existing UPS systems face inefficiencies due to high switching losses in hard switching mode DC-DC converters, which limits power density and requires high efficiency to manage limited electrical energy from batteries.
Innovation Solution
A method of controlling a resonant push-pull converter that includes a transistor, switches, a resonant tank, and a rectifying circuit, using fixed on-time control, frequency switching control, and output voltage control to achieve soft switching and wide-range full-resonance operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hard switching mode is used in DC-DC converters, then the converter structure is simple, but switching losses increase and conversion efficiency decreases
Solution Approach 1:
The patent applies resonant vibration principles by introducing a resonant tank circuit (comprising inductor Lr and capacitor Cr) that operates at a specific resonant frequency. This causes the switching current to naturally oscillate, enabling the main switch to turn off when current is zero (ZCS), thereby eliminating switching losses while maintaining relatively simple circuit structure
Solution Approach 2:
The patent changes the operating parameters by transitioning from hard switching to soft switching mode. Specifically, it modifies the switching characteristics by controlling the switch to operate under zero-current switching (ZCS) conditions through resonant frequency control, which fundamentally changes the energy loss characteristics without significantly complicating the overall converter architecture
2Power
If operation frequency is increased to increase power density, then power density improves, but switching losses increase
Solution Approach 1:
The patent utilizes resonant vibration at the operating frequency to enable soft switching. By designing the resonant tank circuit to operate at the desired high frequency, the system achieves both high power density and zero switching losses, as the resonant oscillation ensures zero-current switching conditions are met regardless of the elevated operating frequency
3Reliability
If battery voltage is limited, then system reliability improves, but output voltage value decreases
Solution Approach 1:
The patent changes the voltage transformation ratio parameter by optimizing the transformer turns ratio (Np:Ns) and operating frequency. This allows the system to achieve higher output voltage from limited battery voltage while maintaining reliable operation, as the resonant push-pull topology provides efficient voltage step-up capability without requiring excessive battery voltage
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves zero switching loss, increases conversion efficiency, reduces transistor surge voltage, and enhances electromagnetic compatibility, allowing for flexible input voltage selection and improved heat dissipation.
Implementation Method 1
resonant push-pull converter includes a transistor, a first switch, a second switch, a resonant tank, and a rectifying circuit
Implementation Method 2
The transistor includes a primary-side winding and a secondary-side winding
Implementation Method 3
The rectifying circuit is coupled to the secondary-side winding, and converts AC power provided by the secondary-side winding into a DC output voltage
Data Source
AI summary
A method of controlling a resonant push-pull converter is disclosed. The resonant push-pull converter includes a transformer, a first switch, a second switch, a resonant tank, and a rectifying circuit. The method includes a step of a fixed on-time control. In the fixed on-time control, a first control signal with a fixed on-time is used to control the first switch, and a second control signal with the fixed on-time is used to control the second switch so that the first switch and the second switch are alternately switched.