Half Bridge Converter Drive Unit With Time Delay Circuits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drive units for half-bridge converters, such as those used in half-bridge flyback converters, face challenges in being cost and size efficient while maintaining low switching losses, with prior solutions either increasing component count and size or being excessively expensive due to the need for complex integrated circuits and high-side drive capabilities.
Innovation Solution
A drive unit utilizing time delay circuits composed of transistors, resistors, capacitors, and diodes to introduce a time delay between switching elements, connected in series at the output terminals of the secondary windings, and incorporating a single output PWM controller for cost-effective and efficient zero current switching, eliminating the need for high-side drive ICs and reducing switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If complex integrated circuits and high-side drive capabilities are used to achieve low switching losses, then switching losses are reduced, but cost and device complexity increase
Solution Approach 1:
The circuit uses the resonant current naturally present in the flyback converter to automatically turn off the high-side switch. The resonant current flowing through the auxiliary winding generates a negative voltage that turns off the high-side MOSFET, eliminating the need for complex active control circuits while achieving zero-current switching and low switching losses.
2Loss of energy
If complex integrated circuits and high-side drive capabilities are used to achieve low switching losses, then switching losses are reduced, but cost increases
Solution Approach 1:
The circuit uses the resonant current naturally present in the flyback converter to automatically turn off the high-side switch. The resonant current flowing through the auxiliary winding generates a negative voltage that turns off the high-side MOSFET, eliminating the need for complex active control circuits while achieving zero-current switching and low switching losses.
3Device complexity
If simple drive units are used to reduce cost and device complexity, then cost and device complexity are reduced, but switching losses increase
Solution Approach 1:
The circuit uses the resonant current naturally present in the flyback converter to automatically turn off the high-side switch. The resonant current flowing through the auxiliary winding generates a negative voltage that turns off the high-side MOSFET, eliminating the need for complex active control circuits while achieving zero-current switching and low switching losses.
Solution Approach 2:
The auxiliary winding provides feedback about the resonant current status to the high-side switch control. When the resonant current flows through the auxiliary winding, it generates a negative voltage that feeds back to turn off the high-side MOSFET, ensuring zero-current switching is achieved automatically based on the actual circuit state.
4Device complexity
If simple drive units are used to reduce cost and device complexity, then cost and device complexity are reduced, but switching efficiency decreases
Solution Approach 1:
The circuit uses the resonant current naturally present in the flyback converter to automatically turn off the high-side switch. The resonant current flowing through the auxiliary winding generates a negative voltage that turns off the high-side MOSFET, eliminating the need for complex active control circuits while achieving zero-current switching and low switching losses.
Solution Approach 2:
The auxiliary winding provides feedback about the resonant current status to the high-side switch control. When the resonant current flows through the auxiliary winding, it generates a negative voltage that feeds back to turn off the high-side MOSFET, ensuring zero-current switching is achieved automatically based on the actual circuit state.
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 proposed drive unit achieves cost and size efficiency with low switching losses by ensuring zero current switching in half-bridge flyback converters, utilizing a self-time shifting pulse transformer and time delay circuits to manage switching operations, thereby reducing overall costs and enhancing power efficiency.
Implementation Method 1
each time delay circuit respectively comprises a transistor, a resistor, a capacitor and a diode. Preferably, said time delay circuits introduce a respective time delay such that one switching element is switched off completely before the other one switching element switches on.
Implementation Method 2
an output transformer having a primary winding connected to said switching stage and a secondary winding
Implementation Method 3
a half bridge rectifier connected to said output transformer, said half bridge rectifier outputting said DC output voltage
Data Source
Figure 1a~1b
Figure 1c~1f
Figure 2(a)~2(c)
AI summary
The invention relates to a drive unit (DU) for a half bridge converter (HBC) and a half-bridge converter (HBC using such a drive unit (DU). The drive unit (DU) comprises a transformer (T2) having a primary winding (T2-1) and two secondary windings (T2-21; T2-22), said primary winding (T2-1) receiving a control pulse signal (CS) from a controller (CNTRL) and said two secondary windings (T2-21, T2-22) outputting a first and second switching pulse signal (S1, S2), said first and second switching pulse signals (S1, S2) being complementary to each other. Furthermore, there are provided a first and a second time delay circuit (TD1, TD2) respectively receiving said first and second complementary switching signal (S1, S2) and introducing a respective time delay (Δt1; Δt2) in said first and second switching signal (S1, S2), said first and second time delayed switching pulse signals (S1'; S2') being fed to a first and second switching element (Q1, Q2) of said half bridge converter (HBC). The drive unit is adopted to drive e.g. a half bridge flyback power converter block via a conventional single output voltage mode PWM controller. The half bridge drive unit together with the half bridge flyback converter provides zero current switching of output diode in a very simple, and size and cost efficient manner.