Gate Driving Circuit for Dead-Time Body Diode Suppression
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Solution Overview
Problem
Conventional power conversion devices experience increased losses and switching element deterioration due to electrical conduction through body diodes during dead times in half bridges, which are not effectively managed by existing gate driving systems.
Innovation Solution
A gate driving system that includes low side and high side gate driving circuits with voltage detection units, comparators, and gate signal generation units to control the switching elements, suppressing dead times by maintaining the low side switching element in an on-state during first and second dead times, thereby reducing current flow through body diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional gate driving systems are used in power conversion devices, then the circuit structure is simple, but losses increase and switching element deterioration occurs due to electrical conduction through body diodes during dead times
Solution Approach 1:
The patent implements feedback control by detecting the voltage between the first and second terminals of the low side switching element and comparing it with a reference voltage. Based on this feedback, the gate signal generation unit adjusts the gate signal to maintain the low side switching element in an on-state during dead times, thereby suppressing body diode conduction and reducing losses.
Solution Approach 2:
The patent introduces a voltage detection unit and a comparator as intermediary components between the control device and the gate driving circuit. These intermediaries detect the actual voltage state and generate appropriate control signals to prevent harmful body diode conduction, resolving the contradiction between simple structure and loss reduction.
2Reliability
If dead times are allowed in half bridge switching, then switching elements can change state safely, but current flows through body diodes causing switching element deterioration
Solution Approach 1:
The patent converts the harmful body diode conduction during dead times into a beneficial state by maintaining the low side switching element in an on-state. The voltage detection and feedback control mechanism ensures that what would normally be a harmful condition (dead time with body diode conduction) becomes a controlled state where the switching element remains reliable without deterioration.
3Loss of energy
If the low side switching element is maintained in on-state during dead times, then losses are reduced, but control precision requirements increase
Solution Approach 1:
The patent applies preliminary action by setting the low side switching element to an on-state before the dead time period begins and maintaining it through the dead time. The voltage detection unit continuously monitors the voltage between terminals, and the feedback control prepares and maintains the switching element in the appropriate state, ensuring losses are reduced without requiring extremely high measurement precision during the critical dead time period.
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
This solution effectively suppresses dead times, reducing losses and switching element deterioration, while enhancing control precision in power conversion devices.
Implementation Method 1
a comparator configured to compare a voltage between the first terminal and the second terminal with a threshold voltage
Data Source
AI summary
A driving circuit comprises: a driving voltage generation unit configured to, in a driving circuit that can drive a first semiconductor switching element (QL) including a first terminal, a second terminal, and a control terminal, supply a driving voltage (Vgl) to the control terminal to switch between on and off of the first semiconductor switching element; a comparator configured to compare a voltage (Vql) between the first terminal and the second terminal with a threshold voltage (Vth1); and a driving signal generation unit that generates a driving signal (Gsl′) to be input to the driving voltage generation unit on the basis of an output from the comparator and a first control signal (Gsl) that is generated by a control device and controls switching of the first semiconductor switching element.