Parallel Si/SiC Switching Circuit for Heat-Suppressed Gate Control
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Solution Overview
Problem
The use of wide bandgap semiconductors like SiC in power elements for inverter devices leads to increased heat and potential defects due to high current and heat generation, especially in small-sized home appliances, necessitating temperature and current detection circuits that increase semiconductor size and cost.
Innovation Solution
A semiconductor device with a parallel circuit of a silicon (Si) and silicon carbide (SiC) switching elements, controlled by a gate drive circuit that adjusts the ON state duration based on input signal thresholds, turning off or reducing the power conduction capability of the SiC element when necessary to prevent heat buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a temperature detection circuit and a current detection circuit are provided to the semiconductor device, then heat in the SiC element can be suppressed, but the size and cost of the semiconductor increase
Solution Approach 1:
The patent extracts the heat suppression function from complex detection circuits and implements it through a simplified gate drive circuit that monitors the ON state duration of the SiC element. By removing the need for separate temperature and current detection circuits, the solution maintains heat suppression capability while significantly reducing device size and complexity.
Solution Approach 2:
The gate drive circuit performs self-monitoring of the SiC element's ON state and automatically adjusts its gate voltage accordingly. This self-service mechanism eliminates the need for external detection circuits, as the gate drive circuit itself detects and responds to conditions that would cause excessive heat generation.
2Loss of energy
If the DC characteristics of the SiC element are excessively improved, then efficiency at low current is improved, but current flowing in the SiC element excessively increases and high heat occurs at a time of increasing current in the motor
Solution Approach 1:
The patent implements dynamic control of the SiC element's gate voltage based on the duration of its ON state. The gate drive circuit continuously adjusts the gate voltage to maintain optimal DC characteristics for efficiency while preventing excessive current flow that would generate high heat. This dynamic adjustment allows the system to adapt to changing operating conditions in real-time.
Solution Approach 2:
The gate drive circuit employs periodic monitoring and adjustment of the SiC element's gate voltage based on the ON state duration. By implementing periodic control actions, the system maintains efficient low-current operation while preventing the buildup of excessive heat during high-current periods, thus balancing efficiency and thermal management.
3Ease of manufacture
If a parallel circuit with SiC-MOSFET and Si-IGBT is used, then cost is reduced by downsizing of the SiC-MOSFET, but heat radiation properties deteriorate due to downsized configuration
Solution Approach 1:
The patent applies local quality control by implementing targeted gate voltage adjustment specifically for the SiC element based on its ON state duration. This localized control approach allows the downsized SiC-MOSFET to maintain adequate heat radiation capability in its specific operational context without requiring an increase in overall device size, thus preserving cost benefits while addressing thermal concerns.
Solution Approach 2:
The gate drive circuit dynamically changes the gate voltage parameter of the SiC element based on the duration of its ON state. By adjusting this electrical parameter, the system optimizes the balance between conduction loss and heat generation in the downsized SiC-MOSFET, maintaining cost-effectiveness while ensuring adequate heat radiation capability through intelligent parameter control.
Data Source
AI summary
An object is to provide a technique capable of suppressing heat occurring in a second semiconductor switching element. A semiconductor device includes a parallel circuit in which a first semiconductor switching element and a second semiconductor switching element are parallelly connected and a gate drive circuit. When a state continuing time which is a time during which the state of the input signal continues is equal to or larger than a threshold value, the gate drive circuit turns off the second semiconductor switching element while keeping ON of the first semiconductor switching element, or reduces a power conduction capability of the second semiconductor switching element while keeping ON of the first semiconductor switching element.