Inverter Protection Circuit for Stable Ground Potential
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Solution Overview
Problem
Conventional inverter protection devices face instability due to floating ground potential, which affects normal operations even when a 5V power is applied to the first power switch.
Innovation Solution
The inverter protection device configures independent power switches and serially connects buffers that are turned on by power transmitted through these switches, ensuring the ground potential remains stable by preventing floating states through the use of first and second insulating units and filter units to remove switching ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first power switch and second power switch are connected in series to control the buffer unit, then the protection function is achieved, but the ground potential becomes unstable and floats when one switch is open
Solution Approach 1:
The patent divides the single buffer unit into two separate buffer units (first buffer unit and second buffer unit), each controlled by its own power switch. This segmentation allows each buffer to maintain stable ground potential independently, preventing the floating ground potential issue that occurs when switches are connected in series in conventional designs.
Solution Approach 2:
The patent introduces a third power switch (third power switch) as an intermediary element connected in parallel with the first and second power switches. This intermediary switch provides an additional current path that prevents ground potential from floating when either the first or second power switch is open, thereby maintaining stable ground potential while preserving the protection function.
2Object-affected harmful factors
If the first insulating unit and second insulating unit are used to isolate voltage signals, then safety is improved, but circuit complexity increases
Solution Approach 1:
The patent makes the third power switch serve multiple functions: it acts as a parallel path for current flow to prevent ground potential floating, and simultaneously functions as an additional protection element in the safety relay circuit. This multi-functionality reduces the need for separate components, thereby limiting the increase in circuit complexity while maintaining enhanced safety.
3Ease of operation
If the buffer unit is controlled by secondary-side voltage of photocouplers, then the control function is achieved, but the ground potential floats when power switches are in series
Solution Approach 1:
The patent segments the control system into two independent control paths, with each buffer unit having its own power switch and insulating unit. This segmentation ensures that the control function is maintained for each buffer independently, while the parallel connection of the third power switch provides a stable ground reference that prevents floating ground potential.
Data Source
AI summary
An inverter protection device is disclosed. An inverter protection device, which determines whether or not a pulse-width modulation (PWM) control signal provided to an inverter unit of an inverter is blocked in accordance with a voltage signal received from first and second switches of a safety relay which are parallelly connected, comprises: a first power switch which is switched to an on-state by means of a first voltage signal applied from the first switch; a second power switch which is switched to an on-state by means of a second voltage signal applied from the second switch; and a buffer unit which is on-off controlled in accordance with an output current of the first and second power switches and provides the PWM control signal to the inverter unit.