Electric Turning Machine Dual Control Strategy for Engine Starting
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Solution Overview
Problem
Existing electric starting systems for internal combustion engines, such as those in small vehicles like snowmobiles, add weight and complexity, reducing fuel efficiency and handling, and require larger motor-generator units to provide sufficient torque for starting, while also facing challenges in voltage control at varying rotational speeds.
Innovation Solution
A system and method using an electric turning machine (ETM) connected to the crankshaft for starting the engine, with a dual-control strategy to manage power delivery, allowing the ETM to operate as both a motor and generator, using a smaller and lighter power source, and adjusting voltage to maintain efficiency across a range of rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electric starting system with battery and starter is used, then the engine can be started reliably, but the vehicle weight increases and fuel efficiency decreases
Solution Approach 1:
The patent combines the starter motor and generator into a single motor-generator unit that is directly coupled to the crankshaft. This integrated unit serves dual functions: providing starting torque when the engine needs to be started and generating electrical power when the engine is running, thereby eliminating the need for separate battery-starter and generator systems and reducing overall vehicle weight.
Solution Approach 2:
The motor-generator unit is designed to perform multiple functions: it operates as a motor during engine starting to provide high torque, and as a generator during engine operation to produce electrical power. This multi-functionality allows a single component to replace what would traditionally require multiple separate components, reducing weight and complexity.
2Device complexity
If a motor-generator unit is used to replace separate starter and generator, then weight and complexity are reduced, but the unit must be sufficiently large to provide adequate starting torque
Solution Approach 1:
The control system dynamically switches the motor-generator unit between motor mode and generator mode based on engine operating conditions. During starting, the unit operates as a motor providing high torque; during engine operation, it switches to generator mode. This dynamic operation allows the unit to be optimized for both high torque delivery and efficient power generation without requiring excessive size.
Solution Approach 2:
The system changes operational parameters (rotational speed, current direction, magnetic field orientation) to optimize the motor-generator unit's performance across different operating modes. By adjusting these parameters, the unit can deliver high starting torque when needed while maintaining a compact size through efficient parameter management during generation mode.
3Power
If the motor-generator operates at high rotational speeds as a generator, then electrical power is produced, but voltage control becomes challenging to match component needs
Solution Approach 1:
The control system incorporates feedback mechanisms that continuously monitor the voltage output of the motor-generator unit and adjust the field current or switching parameters to maintain the desired voltage level. This feedback control allows the system to manage high-speed generation effectively while keeping voltage within acceptable ranges for various vehicle components.
Solution Approach 2:
The system dynamically adjusts the motor-generator's operational parameters based on real-time conditions. During generation mode, the control system modifies field excitation, switching frequency, or connection configuration to regulate voltage output despite variations in rotational speed, thereby simplifying voltage control across the operating range.
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 enables efficient and lightweight electric starting of internal combustion engines, reducing weight and complexity, while maintaining performance and fuel efficiency by optimizing power delivery and voltage control.
Implementation Method 1
delivering electric power from a power source to the electric turning machine to rotate the crankshaft
Implementation Method 2
the electric turning machine operates as a generator, delivering electric power from the electric turning machine
Data Source
AI summary
An electric turning machine (ETM) operatively connected to an internal combustion engine (ICE) is operated as a motor with a first control strategy and as a generator with a second control strategy. In the first control strategy, electric power is delivered from a power source to the ETM selectively through at least one transistor of an electrical converter. After switching from the first control strategy to the second control strategy, the ETM delivers electric power to an accessory selectively through the at least one transistor of the electrical converter.