Inverter Arm Gate-Voltage Control for Crosstalk Overvoltage
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Solution Overview
Problem
Inverter arms with wide-gap transistors experience crosstalk phenomena leading to transient overvoltages that damage components, with existing solutions either increasing switching losses or providing partial relief, necessitating dedicated circuits for each transistor.
Innovation Solution
A control circuit adjusts the gate-source voltage of transistors in an inverter arm using a control scheme that includes increasing the voltage during one switch's deactivation and reducing it during the other's activation, employing a single circuit to manage multiple transistors in parallel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the gate resistor value is increased to reduce switching speed and overvoltages, then transient overvoltages are reduced, but switching losses increase
Solution Approach 1:
The control circuit proactively adjusts the gate-source voltage before the harmful transient phenomena occur. During the deactivation period, the circuit increases the gate-source voltage in advance before the other switch activates, preventing negative overvoltage damage. During activation, it reduces the gate-source voltage before the other switch deactivates, preventing positive overvoltage and short-circuit risks. This preliminary action eliminates the need for increased gate resistor values while maintaining low switching losses.
Solution Approach 2:
The invention dynamically changes the gate-source voltage parameter during different switching periods. Instead of using a fixed high gate resistor value that increases switching losses, the circuit actively modulates the gate-source voltage level - increasing it during deactivation periods and reducing it during activation periods - to counteract transient overvoltages while preserving fast switching performance and low energy losses.
2Reliability
If dedicated control circuits are added for each transistor to manage transient overvoltages, then component reliability improves, but device complexity increases
Solution Approach 1:
The invention merges the control of multiple parallel transistors into a single control circuit. Instead of implementing separate dedicated control circuits for each transistor (which would increase device complexity), one control circuit manages all transistors in parallel by adjusting the gate-source voltage of each transistor according to the switching state of the other transistors. This unified approach maintains component reliability while avoiding the complexity of multiple independent control circuits.
Solution Approach 2:
The control circuit performs multiple functions: it controls the switching of transistors, monitors the switching periods of other switches, and dynamically adjusts gate-source voltages to prevent transient overvoltages. This multi-functional approach replaces what would otherwise require separate dedicated circuits for each transistor, reducing overall device complexity while maintaining reliability.
Data Source
AI summary
A control circuit for a first switch includes at least one transistor, the first switch being arranged in series with a second switch in an inverter arm of an electrical power supply device supplying a load connected to the mid-point of the series arrangement of the first and second switch. The control circuit is configured to adjust the gate-source voltage of the at least one transistor of the first switch according to a control scheme including, during a deactivation period of the first switch, the increase of the gate-source voltage in a time window including the deactivation of the second switch and the reduction of the gate-source voltage in a time window including the activation of the second switch.