Multiplexing AC Ignition Drive Circuit with PWM Control
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Solution Overview
Problem
Conventional ignition systems for internal combustion engines, such as capacitive discharge and inductive systems, lack adjustability and reliability, and AC systems are costly and complex with limited real-time control over spark discharge characteristics and fault diagnosis.
Innovation Solution
A programmable AC ignition system with a multiplexing drive circuit using a common leg and dedicated legs with pulse-width modulated switches, a transformer with a two-winding ignition coil, and a programmable controller for precise control of spark discharge characteristics and fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional capacitive discharge or inductive ignition systems are used, then the system structure is simple, but the adjustability of spark discharge characteristics (CA and SD) is limited and they cannot be adjusted independently
Solution Approach 1:
The patent implements dynamic control of the ignition system by using pulse-width modulated switches that can be independently controlled to adjust current amplitude and spark duration. The system transitions from static energy storage to dynamic real-time control, allowing independent adjustment of CA and SD parameters during operation rather than requiring fixed coil designs.
Solution Approach 2:
The patent changes the operational parameters of the ignition system by using programmable control to vary the duty cycle and timing of the pulse-width modulated switches. This allows the system to adjust electrical parameters (current amplitude, spark duration) independently without changing the physical coil design, resolving the contradiction between adaptability and complexity.
2Adaptability or versatility
If AC ignition systems with multiple power semiconductors or complex coil windings are used, then spark discharge control is improved, but the component count and system cost increase
Solution Approach 1:
The patent merges multiple control functions into a single programmable controller that manages pulse-width modulated switches. By integrating the control logic and using multiplexing techniques, the system achieves real-time control of spark discharge characteristics without requiring separate dedicated circuits for each function, thereby reducing overall component count while maintaining control capability.
Solution Approach 2:
The programmable controller serves multiple functions including real-time control of spark discharge characteristics, fault detection, and system diagnostics. This multi-functional approach eliminates the need for separate dedicated components for each function, reducing component count while maintaining comprehensive control and monitoring capabilities.
3Reliability
If conventional ignition systems are used, then the system is simpler, but fault detection and system diagnostics are not available
Solution Approach 1:
The patent implements feedback mechanisms where the programmable controller continuously monitors system parameters and provides real-time diagnostics. The system uses the same pulse-width modulated control circuitry to both operate the ignition and detect faults, with the controller analyzing electrical characteristics to identify issues such as coil failures or improper spark discharge, thereby adding reliability without requiring entirely separate diagnostic hardware.
4Adaptability or versatility
If energy is increased in the magnetic core, then open circuit voltage, current amplitude, and spark duration increase, but the parameters cannot be adjusted independently and are predetermined by the coil design
Solution Approach 1:
The patent makes the ignition system dynamic by using pulse-width modulated switches controlled by a programmable controller. This allows real-time adjustment of current amplitude and spark duration independently of the coil's fixed physical characteristics. The system can modify energy delivery parameters on-the-fly without requiring multiple coil designs or modifications to the magnetic core structure.
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 system allows for adjustable spark discharge characteristics, reduced component count and cost, and enhanced reliability with real-time control and self-diagnostic capabilities, enabling efficient operation across various engine conditions.
Implementation Method 1
a transformer (with two-winding ignition coil) for each of the one or more dedicated legs, each transformer having a primary winding coupled between one of the one or more dedicated legs and the common leg. Furthermore, each transformer has a secondary winding coupled in parallel to a spark plug
Implementation Method 2
A multiplexing drive circuit for an AC ignition system having a common leg that includes two switches coupled in series, and one or more dedicated legs, wherein each dedicated leg includes two switches coupled in series... a pulse-width modulated (PWM) switch controller configured to operate the common leg and dedicated leg switches to control characteristics of the spark discharge
Data Source
AI summary
A multiplexing drive circuit for an AC ignition system having a common leg that includes two switches coupled in series, and one or more dedicated legs, wherein each leg includes two switches coupled in series. The multiplexing drive circuit also includes a transformer for each of the one or more dedicated legs, each transformer having a primary winding coupled between one of the one or more dedicated legs and the common leg, and wherein each transformer has a secondary winding coupled in parallel to a spark plug, and a pulse-width modulated (PWM) switch controller configured to operate the common leg and dedicated leg switches to control characteristics of the spark discharge for the spark plug. Wherein the switch controller is capable of real time diagnostic checks by monitoring the time at which a spark discharge event takes place.