Gate Drive Circuit Charge Recovery for Semiconductor Switching
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Solution Overview
Problem
The existing gate drive circuit with a reactor in the auxiliary drive unit faces issues with voltage exceeding breakdown voltage between the gate and source, potentially damaging the semiconductor element, and reduces switching speed and on-state resistance due to unequal rated voltages for positive and negative electrodes, and excessive power consumption.
Innovation Solution
A gate drive circuit with a recovery circuit comprising series-connected recovery switches, reactors, and capacitors on both positive and negative electrodes to recover charge accumulated in the input capacitance of the semiconductor element, allowing for reduced power supply voltages and efficient power compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reactor is used in the auxiliary drive unit to reduce conduction loss, then conduction loss is reduced, but voltage may exceed breakdown voltage between gate and source
Solution Approach 1:
The patent introduces controllable switching elements (first and second switching elements) in the auxiliary drive unit to dynamically control the reactor connection. By changing the switching states, the circuit can operate with the reactor connected during normal operation to reduce conduction loss, and disconnect or bypass the reactor when voltage approaches breakdown levels, thus adapting the parameter configuration to avoid voltage breakdown while maintaining low conduction loss during normal operation.
2Loss of energy
If a reactor is used in the auxiliary drive unit, then conduction loss is reduced, but switching speed decreases
Solution Approach 1:
The patent makes the auxiliary drive unit dynamic by introducing controllable switching elements that can change the circuit configuration in real-time. The first and second switching elements allow the reactor to be connected or disconnected based on operational requirements, enabling the system to achieve low conduction loss when the reactor is connected and fast switching when the reactor is bypassed, thus resolving the contradiction between conduction loss reduction and switching speed.
3Reliability
If unequal rated voltages are applied to positive and negative electrodes, then breakdown voltage is respected, but on-state resistance increases
Solution Approach 1:
The patent segments the power supply configuration by providing separate first and second power supplies with different voltage levels for the positive and negative electrodes. The first power supply provides a higher voltage to the positive electrode while the second power supply provides a lower voltage to the negative electrode, allowing each electrode to operate within its safe breakdown voltage limits while maintaining appropriate current flow characteristics to minimize on-state resistance.
4Reliability
If lower voltage is specified for gate power supply to prevent breakdown, then breakdown voltage is respected, but switching performance deteriorates
Solution Approach 1:
The patent employs dynamic voltage control through controllable switching elements in the auxiliary drive unit. During switching transitions, the circuit can temporarily provide higher voltage to achieve fast switching performance, while during steady-state operation, the voltage is maintained at safe levels to prevent breakdown. This dynamic adjustment of voltage levels resolves the contradiction between breakdown voltage compliance and switching performance.
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 design reduces the total power of the gate power supply, minimizes the size of the power supply circuit, and prevents voltage exceeding breakdown limits, enhancing switching speed and on-state resistance while maintaining reliability.
Implementation Method 1
an LC resonant circuit being configured of the reactor and the parasitic capacitance of the drive target semiconductor element gate
Data Source
AI summary
A gate drive circuit including a drive-on element that applies an on-state voltage to a gate of a drive target semiconductor element and a drive-off element that applies an off-state voltage to the gate is such that a recovery switch, a reactor, and a capacitor are connected in series between output terminals of the gate drive circuit as a recovery circuit that can recover a charge accumulated in input capacitance of the drive target semiconductor element when turning on, and the drive-on element, the drive-off element, and the recovery switch are controlled by a control circuit, whereby power consumption of the gate drive circuit is reduced.