HVDC Semiconductor Switching Circuit with Auxiliary Voltage Control
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Solution Overview
Problem
Semiconductor switching elements in HVDC power converters exhibit varying performance characteristics, leading to operational difficulties and the need for large, heavy remedial components to compensate for these differences, which complicates the conversion process.
Innovation Solution
A semiconductor switching circuit with a main semiconductor switching element and an auxiliary switching element, controlled by a programmed control unit to create an alternative current path, allowing for operation in fully-on, pulsed switched, and active modes to manage voltage and current, thereby compensating for performance variations and optimizing power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If semiconductor switching elements from different batches and suppliers are used, then device versatility and availability are improved, but performance characteristic variations increase causing operational difficulties
Solution Approach 1:
An auxiliary semiconductor switching element is introduced as an intermediary component between the power circuit and the main semiconductor switching element. This auxiliary element acts as a mediator that compensates for performance variations in the main element, allowing elements from different batches and suppliers to be used while maintaining operational reliability. The auxiliary element's switching characteristics are designed to counterbalance the variations in the main element.
Solution Approach 2:
The invention changes the switching parameters of the auxiliary semiconductor switching element dynamically to compensate for performance variations in the main element. By adjusting the auxiliary element's switching timing, duty cycle, and gate drive parameters, the system can accommodate main elements with different performance characteristics from various manufacturers and batches, thus resolving the contradiction between versatility and reliability.
2Reliability
If large remedial components are added to compensate for semiconductor switching element limitations, then performance compensation is improved, but device complexity, weight and design difficulty increase
Solution Approach 1:
Instead of using large, complex remedial components, the invention employs a compact auxiliary semiconductor switching element as an intermediary. This auxiliary element provides the necessary performance compensation through controlled switching actions, replacing the need for bulky passive components while reducing overall device complexity and design difficulty.
Solution Approach 2:
The invention replaces traditional mechanical or passive remedial components with an active semiconductor-based solution. The auxiliary semiconductor switching element uses electronic control mechanisms rather than mechanical adjustments or large passive components, thereby reducing device complexity, weight, and design difficulty while maintaining performance compensation capability.
3Ease of operation
If the auxiliary semiconductor switching element is operated in fully-on mode continuously, then current path control is simplified, but power dissipation increases
Solution Approach 1:
The auxiliary semiconductor switching element operates in periodic pulsed mode rather than continuous fully-on mode. By applying periodic gate signals with appropriate duty cycles, the auxiliary element creates the necessary alternative current paths only when required, simplifying control logic while minimizing continuous power dissipation. The pulsed operation allows the element to remain off during periods when compensation is not needed.
Solution Approach 2:
The invention dynamically adjusts the auxiliary semiconductor switching element's operating state based on real-time circuit conditions. Rather than maintaining a static fully-on state, the auxiliary element transitions between on and off states dynamically, optimizing the balance between ease of operation and power dissipation. This dynamic control allows simplified operation during critical periods while reducing power loss during non-critical periods.
Data Source
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AI summary
There is provided a semiconductor switching circuit, for use in a HVDC power converter, comprising: a main semiconductor switching element (12) including first and second connection terminals (14,16) between which current flows from the first connection terminal (14) to the second connection terminal (16) when the main semiconductor switching element (12) is switched on, the main semiconductor switching element (12) having an auxiliary semiconductor switching element (28) electrically connected between the first and second connection terminals (14,16) thereof; and a control unit (30) operatively connected with the auxiliary semiconductor switching element (28), the control unit (30) being programmed to control switching of the auxiliary semiconductor switching element (28) in a given operating cycle to selectively create an alternative current path (32) between the first and second connection terminals (14,16) associated therewith whereby current is diverted to flow through the alternative current path (32) to reduce the voltage across the main semiconductor switching element (12), wherein the switching of the auxiliary semiconductor switching element (28) in a given operating cycle to create the alternative current path (32) includes operation of the auxiliary semiconductor switching element (28) in at least two of: (i) a fully-on mode in which the auxiliary semiconductor switching element (28) is operated with its maximum rated base current or gate voltage; (ii) a pulsed switched mode in which the auxiliary semiconductor switching element (28) is turned on and off; and (iii) an active mode in which the auxiliary semiconductor switching element (28) is operated with a continuously variable base current or gate voltage.