Generator Field Coil De-energization Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing generator control circuits are inefficient in quickly and reliably de-energizing field coils during load dumps, leading to prolonged surge voltages that can damage electrical components.
Innovation Solution
A driver circuit with two half bridges and controllable semiconductor switches, along with diodes, is used to manage current flow through the field coil, allowing for rapid de-energization by applying a counter voltage higher than the system voltage during load dumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expensive power zener diodes are used to de-energize the field coil, then surge voltage protection is improved, but device cost and complexity increase
Solution Approach 1:
The circuit is divided into two half-bridge circuits, each with controllable semiconductor switches (MOSFETs or IGBTs) that can independently control current flow through the field coil. This segmentation allows precise control of the de-energization process without requiring expensive protective components like power zener diodes.
Solution Approach 2:
The invention changes the voltage parameter applied to the field coil during de-energization by utilizing the second battery's higher voltage potential. This parameter change enables faster collapse of magnetic flux and more effective surge voltage suppression through controlled reverse current flow.
2Device complexity
If traditional de-energization circuits are used, then circuit simplicity is maintained, but magnetic energy dissipation time increases
Solution Approach 1:
The second battery is pre-charged to a higher voltage potential during normal operation, preparing the energy storage system in advance. When de-energization is required, this pre-stored energy is immediately available to drive reverse current through the field coil, enabling rapid magnetic energy dissipation without adding complex active switching circuits.
Solution Approach 2:
The circuit enables periodic reversal of current direction through the field coil by alternately activating switches in different half-bridges. This periodic action accelerates magnetic energy dissipation by repeatedly collapsing and reversing the magnetic flux, reducing the overall de-energization time.
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
The solution effectively reduces the magnetic energy stored in the field coil more quickly than traditional methods, minimizing surge voltage duration and amplitude, thus protecting generator components.
Implementation Method 1
During normal operation, current is supplied to the field coil thus generating a desired magnetic field
Implementation Method 2
A driver circuit with two half bridges and controllable semiconductor switches, along with diodes, is used to manage current flow through the field coil, allowing for rapid de-energization by applying a counter voltage higher than the system voltage during load dumps
Data Source
AI summary
A circuit includes a first half bridge including a first controllable semiconductor switch and a first diode. The first controllable semiconductor switch is coupled between a first constant supply potential and a center tap of the first half bridge. The first diode is coupled between the center tap and a constant reference potential. A second half bridge includes a second diode and a second controllable semiconductor switch. The second diode is coupled between a second constant potential higher than the first potential and a center tap of the second half bridge. The second controllable semiconductor switch is coupled between the center tap and the constant reference potential. Driver circuitry controls the conducting state of the first and the second semiconductor switch thus controlling the current flow through a field connectable between the center taps.