Bootstrap Driver Supply Circuit Using an Auxiliary Capacitor
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Solution Overview
Problem
Existing power electronics devices face challenges in efficiently supplying electrical voltage to driver circuits, particularly for power semiconductor switches like MOSFETs or IGBTs, especially during startup and operation, due to the inefficiency of current methods which often result in low efficiency and limited suitability for continuous operation.
Innovation Solution
The implementation of an auxiliary circuit arrangement that includes a supply capacitor, an auxiliary capacitor, a normally off auxiliary semiconductor switch, and a bootstrap diode, which allows for efficient charging of the supply capacitor from the auxiliary capacitor, ensuring reliable voltage supply to the driver circuit without interfering with the main function of the power electronics device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional voltage supply method is used for the driver circuit, then the device complexity is reduced, but the efficiency of voltage supply is low and continuous operation is limited
Solution Approach 1:
The auxiliary capacitor is integrated into the main power circuit, merging the voltage supply function with the existing power conversion circuitry. This allows the auxiliary capacitor to be charged during normal operation without requiring a completely separate power supply system, thereby improving efficiency while controlling complexity.
Solution Approach 2:
The auxiliary circuit arrangement serves multiple functions: the auxiliary capacitor provides voltage supply to the driver circuit, the bootstrap diode enables voltage transfer, and the auxiliary switch controls charging/discharging cycles. This multi-functionality allows a single circuit arrangement to handle both power conversion and driver supply tasks.
2Reliability
If an auxiliary circuit arrangement is implemented for efficient voltage supply, then the efficiency and continuous operation capability are improved, but the device complexity increases
Solution Approach 1:
The auxiliary capacitor is charged in advance during the off-state of the power semiconductor switch, before it is needed to supply the driver circuit. This preliminary charging action ensures that sufficient voltage is available for continuous operation without interrupting the main power conversion function.
Solution Approach 2:
The auxiliary capacitor is charged and discharged in periodic cycles synchronized with the switching of the power semiconductor switch. During each off-state period, the capacitor charges; during each on-state period, it supplies voltage to the driver circuit. This periodic operation ensures continuous reliability while using simple switching control.
3Duration of action of moving object
If the auxiliary switch is normally on, then the voltage supply is continuous, but the main function of the power electronics device is interfered with
Solution Approach 1:
The auxiliary switch dynamically changes state between on and off positions in synchronization with the main power switch. This dynamic operation allows the auxiliary capacitor to charge during off-periods and discharge during on-periods, providing continuous driver supply without interfering with the main power conversion function.
Solution Approach 2:
The auxiliary capacitor provides continuous voltage supply to the driver circuit by being recharged during each off-state period of the power switch. This ensures uninterrupted operation of the driver circuit while the auxiliary switch remains normally off, preventing interference with the main power electronics function.
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 enables efficient voltage supply to the driver circuit, both during startup and operation, with minimal impact on the main function of the power electronics device, using a normally off auxiliary switch that behaves like a section of an electrical connection, thus maintaining high efficiency and operational stability.
Implementation Method 1
a bootstrap diode. The auxiliary semiconductor switch is connected to a reference potential connection of the first power semiconductor switch via a first connection point
Implementation Method 2
an auxiliary capacitor, a normally off auxiliary semiconductor switch, a diode and a bootstrap diode. Starting from the first connection point, a series connection of the diode, a second connection point and the auxiliary capacitor is arranged in parallel with the auxiliary semiconductor switch
Data Source
AI summary
A power electronics device has a first power semiconductor switch and a driver circuit and enables a supply of electrical voltage to a driver circuit. An auxiliary circuit arrangement has a supply capacitor, an auxiliary capacitor, a normally off auxiliary semiconductor switch, a diode and a bootstrap diode. The auxiliary semiconductor switch is connected to a reference potential connection of the first power semiconductor switch via a connection point, starting from the connection point, a series connection of the diode, a second connection point and the auxiliary capacitor is arranged in parallel with the auxiliary semiconductor switch. When the auxiliary semiconductor switch is in the off state, the auxiliary capacitor is charged by the flow of current through the first power semiconductor switch.