Dual Bootstrap Circuit for Stable High-Side Driver Voltage
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Solution Overview
Problem
Existing circuit arrangements for supplying voltage to high-side transistor driver circuits in power semiconductor modules face challenges in maintaining a stable voltage supply without high-voltage-resistant semiconductor components, often resulting in significant power loss and limited duration of operation due to the reliance on capacitors and charge pumps that require floating voltage supplies.
Innovation Solution
A dual-bootstrap circuit arrangement is implemented, comprising two bootstrap circuits with capacitors and charge pumps, where one bootstrap circuit is supplied with a lower auxiliary voltage and the other with an upper auxiliary voltage, allowing the second charge pump to generate the necessary voltage for the first charge pump, thereby maintaining a stable supply voltage for the driver circuit without high-voltage-resistant components and minimizing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a bootstrap circuit with a capacitor is used to supply voltage to the driver circuit, then the driver circuit can be supplied in a floating manner, but the capacitor cannot store sufficient charge to maintain the supply for a sufficient amount of time
Solution Approach 1:
The patent combines a bootstrap circuit and a charge pump circuit into a hybrid voltage supply system. The bootstrap circuit provides initial voltage storage while the charge pump circuit continuously replenishes charge to the bootstrap capacitor, extending the duration of voltage supply without requiring an oversized capacitor alone.
Solution Approach 2:
The charge pump circuit is designed to proactively recharge the bootstrap capacitor before its charge is depleted, ensuring continuous voltage supply to the driver circuit. This preliminary charging action prevents voltage dropout and extends operational duration.
2Reliability
If a charge pump is added to supplement the bootstrap circuit, then the capacitor can be kept charged, but the clock generator of the charge pump requires a floating voltage supply which consumes considerable power loss
Solution Approach 1:
The voltage supply system is segmented into two independent parts: a first voltage supply circuit for the driver circuit and a second voltage supply circuit for the charge pump clock generator. This segmentation allows each part to be optimized independently, with the second circuit using a ground-referenced design that consumes less power.
Solution Approach 2:
The patent introduces an intermediary voltage conversion stage that converts the ground-referenced voltage from the second supply circuit into the floating voltage required by the charge pump clock generator. This intermediary conversion allows the use of more efficient ground-referenced components while still providing the required floating voltage.
3Reliability
If high-voltage-resistant semiconductor components are used in the voltage supply circuit, then the circuit can handle high voltages, but the space required and production complexity increase
Solution Approach 1:
The voltage supply circuit is divided into segments with different voltage stress requirements. Only the components directly exposed to high voltage (such as the bootstrap diode and capacitor) are required to be high-voltage-resistant, while the charge pump and its clock generator can use standard low-voltage components, reducing overall complexity.
Solution Approach 2:
High-voltage resistance is applied locally only where absolutely necessary (in the bootstrap portion of the circuit), while the charge pump portion uses standard components. This localized application of high-voltage rating reduces space and production complexity while maintaining overall high-voltage capability.
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 a stable and extended voltage supply to the driver circuit without the need for high-voltage-resistant semiconductor components, reducing power loss and allowing for uninterrupted operation, even with high supply currents.
Implementation Method 1
a first charge pump which is designed to keep the charge in the capacitor at or above a particular level
Implementation Method 2
a second charge pump which is designed to generate the second auxiliary voltage
Data Source
AI summary
The invention relates to a circuit arrangement for providing a voltage supply for a driver circuit for driving a semiconductor switch. The circuit arrangement has: a first bootstrap circuit which is supplied with a first auxiliary voltage referring to a lower supply potential, the bootstrap circuit comprising a first capacitor which provides a supply voltage for the driver circuit; a first charge pump which is designed to keep the charge in the first capacitor at or above a particular level at least during a particular period of time; a second bootstrap circuit which is supplied with a second auxiliary voltage referring to an upper supply potential, the bootstrap circuit comprising a second capacitor which provides a supply voltage for the first charge pump; and a second charge pump which is designed to generate the second auxiliary voltage.