HV Switch Balancing Circuit for Series Switch Voltage Equalization
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Solution Overview
Problem
Existing high voltage (HV) switch units with semiconductor switches connected in series face significant voltage imbalances due to imperfect driver synchronization, parasitic circuit components, and semiconductor property deviations, leading to potential failure from overvoltage or thermal overload, especially at higher voltages and switching frequencies.
Innovation Solution
The implementation of a high voltage switch unit that includes semiconductor switches connected in series, snubber energy storage and rectifying components in parallel with each switch, and a voltage balancing circuit comprising a chain of rectifying electronic components and a voltage limiting component. This configuration ensures equalization of voltages across the switches and limits voltage at the end of the chain, thereby preventing overvoltage and thermal overload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If semiconductor switches are connected in series to operate as one HV switch, then the voltage handling capability is improved, but voltage imbalance among individual switches occurs due to imperfect driver synchronization, parasitic components, and semiconductor property deviations
Solution Approach 1:
A voltage balancing circuit is introduced as an intermediary component between the semiconductor switches. This circuit includes voltage limiting electronic components and balancing components that actively monitor and adjust voltage distribution across the series-connected switches, preventing overvoltage conditions and ensuring reliable operation.
Solution Approach 2:
The voltage balancing circuit dynamically changes electrical parameters (voltage distribution) across the semiconductor switches by using voltage limiting components and balancing electronics. This allows the system to adapt to variations in switch characteristics and maintain balanced voltage levels despite manufacturing tolerances and operating conditions.
2Speed
If clamp-and-discharge circuits are placed locally on each semiconductor switch, then fast clamping and discharge capability is improved, but device complexity increases due to requiring multiple voltage-limiter circuits
Solution Approach 1:
Multiple individual voltage-limiter circuits are merged into a single shared voltage balancing circuit that serves all semiconductor switches. This circuit uses a chain configuration with voltage limiting electronic components that can collectively protect all switches, reducing component count while maintaining protection speed and effectiveness.
Solution Approach 2:
The voltage balancing circuit is designed with multi-functionality to serve multiple purposes: it provides voltage limiting, voltage balancing, and charge transport functions across all semiconductor switches simultaneously. This universal circuit replaces the need for dedicated individual protection circuits for each switch.
3Power
If higher voltage and switching frequency are used, then power capability is improved, but voltage imbalance and risk of overvoltage or thermal overload increase significantly
Solution Approach 1:
The voltage balancing circuit incorporates feedback mechanisms through voltage limiting electronic components that continuously monitor voltage levels across the semiconductor switches. When voltage imbalance or overvoltage conditions are detected, the circuit automatically adjusts to redistribute voltage, providing real-time protection that enables higher power operation with maintained reliability.
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 effectively mitigates voltage imbalances among semiconductor switches, ensuring even energy dissipation and preventing failures due to overvoltage or thermal overload, thereby enhancing the reliability and performance of HV switch units, especially at higher voltages and frequencies.
Implementation Method 1
Each series circuit includes a snubber energy storage component and a snubber rectifying component. Each series circuit is connected parallel to each respective semiconductor switch. The plurality of balancing electronic components forms a chain parallel to the serially connected semiconductor switches. The chain is configured to transport electrical charge from one snubber energy storage component to the next snubber energy storage component only in one direction.
Implementation Method 2
The voltage limiting electronic component is configured to limit a voltage at an end of the chain, where the electrical charge is transported to.
Data Source
AI summary
A high voltage (HV) switch unit includes a plurality of semiconductor switches connected with each other in series and configured to switch on and off simultaneously, and a plurality of series circuits. Each series circuit includes a snubber energy storage component and a snubber rectifying component. Each series circuit is connected parallel to each respective semiconductor switch. The HV switch unit further includes a voltage balancing circuit comprising a plurality of balancing electronic components in combination with a voltage limiting electronic component. The plurality of balancing electronic components forms a chain parallel to the serially connected semiconductor switches. The chain is configured to transport electrical charge from one snubber energy storage component to the next only in one direction. The voltage limiting electronic component is configured to limit a voltage at an end of the chain, where the electrical charge is transported to.