IGBT Switch Sequential Turn-Off for Surge Voltage Reduction
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Solution Overview
Problem
Existing power supply devices experience significant surge voltage generation and prolonged switching off times due to the simultaneous turn-off of multiple switching elements, which can lead to increased maintenance costs and reduced service life of components.
Innovation Solution
The power supply device divides switching elements into two groups, allowing for sequential turn-off, where the first group is turned off before the second group, reducing surge voltage and enabling quicker switch deactivation without waiting for alternating current to reach zero.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple switching elements are turned off simultaneously, then the switch can be turned off quickly, but a large surge voltage is generated between the terminals of the switch
Solution Approach 1:
The switching elements are divided into a first group and a second group. The controller turns off the switching elements in the first group before turning off the switching elements in the second group. This segmentation of the turn-off process allows for reduced surge voltage while maintaining relatively quick switch deactivation.
Solution Approach 2:
The controller performs a preliminary action by turning off the switching elements in the first group before turning off the switching elements in the second group. This preliminary turn-off of the first group reduces the surge voltage that would otherwise be generated when all switching elements are turned off simultaneously.
2Object-generated harmful factors
If the switch is turned off by waiting for alternating current to reach the zero point, then surge voltage is reduced, but the switch cannot be turned off quickly
Solution Approach 1:
The switching elements are divided into two groups with different turn-off timings. The first group is turned off before the alternating current reaches zero, while the second group is turned off after. This segmentation allows the switch to be turned off without waiting for the zero point, reducing time loss while managing surge voltage.
Solution Approach 2:
The controller performs a preliminary turn-off of the first group of switching elements before the alternating current reaches zero. This preliminary action enables the switch to be deactivated more quickly than waiting for the zero point, while still controlling surge voltage through the sequential turn-off of the second group.
3Device complexity
If multiple switching elements are turned off at the same time, then the control process is simple, but the service life of surge absorbers is reduced due to large surge voltage
Solution Approach 1:
The switching elements are divided into two groups, and the controller manages their turn-off sequentially. While this increases control complexity compared to simultaneous turn-off, it significantly reduces surge voltage, thereby extending the service life of surge absorbers and reducing maintenance needs.
Solution Approach 2:
The controller performs a preliminary turn-off of the first group of switching elements, which reduces the surge voltage that reaches the surge absorbers. This preliminary action, while adding control complexity, protects the surge absorbers from excessive voltage stress, extending their service life and reducing maintenance requirements.
Data Source
AI summary
The uninterruptible power supply device includes a switch (2) that includes first to Nth IGBT units (U1 to UN) connected in series, and a controller that turns on the switch by turning on the first to Nth IGBT units, and turns off the switch by firstly turning off the first to nth IGBT units and then turning off the (n+1)th to Nth IGBT units. Compared with the case where the first to Nth IGBT units are turned off at the same time, it is possible to reduce a surge voltage generated between the terminals of the switch (2).