Sensorless Cranking of Internal Combustion Engine via Stator Current
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Solution Overview
Problem
Conventional Integrated Starter Generator (ISG) systems for internal combustion engines face issues with sensor failure due to harsh operating conditions, increased cost, and space occupancy, as well as wire damage, which affects the reliability and efficiency of the system.
Innovation Solution
A method and system for cranking an internal combustion engine using a permanent magnet machine that determines the initial and updated rotor position by measuring stator current variations and applying pulse-width-modulated signals to the stator windings, eliminating the need for sensors by leveraging the ECU to control the excitation sequence based on current measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hall-effect sensors or absolute angle sensors are used to sense rotor position, then the rotor position can be accurately detected, but the sensors are subjected to harsh operating conditions (high temperature and vibrations) which makes them prone to failure, occupies space inside engine casing, and requires additional wiring
Solution Approach 1:
The patent extracts and eliminates the sensor component from the system by using sensorless control. The rotor position is determined indirectly through mathematical algorithms based on stator current measurements and voltage equations, rather than using physical sensors inside the engine casing. This removes the reliability issues associated with sensors operating in harsh conditions.
Solution Approach 2:
The patent replaces the mechanical/electrical sensor system with an electronic/software-based solution. Instead of using physical sensors to detect rotor position, the system uses electrical measurements (stator currents) and computational algorithms to estimate rotor position, thereby eliminating the need for sensors and their associated wiring.
2Measurement precision
If sensors are placed inside engine casing for rotor position sensing, then rotor position can be measured, but it occupies space inside the engine casing and requires special mounting arrangements which increases cost
Solution Approach 1:
The patent removes the sensor component entirely from the system architecture. Rotor position measurement is achieved through sensorless field-oriented control using stator current measurements and mathematical models, eliminating the need for physical sensors, mounting arrangements, and associated complexity.
Solution Approach 2:
The stator windings serve multiple functions: they are used for both generating torque and for sensing rotor position information through current measurements. This multi-functionality eliminates the need for separate sensor components and their mounting infrastructure.
3Loss of information
If wires are used to connect sensors to ECU for signal transmission, then sensor signals can be transmitted to control unit, but the wires are vulnerable to damage which impairs operation of the ISG system
Solution Approach 1:
The patent eliminates the wiring infrastructure by removing the sensor component. Since no physical sensors are installed, there are no wires required to transmit sensor signals to the ECU, thereby eliminating the reliability issues associated with wire damage in the harsh engine environment.
Solution Approach 2:
The patent replaces the physical wiring system with a sensorless control approach. Rotor position information is derived computationally from stator current measurements that are already part of the control system, eliminating the need for separate signal transmission pathways and vulnerable wire connections.
4Measurement precision
If multiple hall-effect sensors are used for rotor position sensing, then accurate rotor position detection is achieved, but it increases cost and requires routing provisions for wires from sensors to ECU
Solution Approach 1:
The patent removes all sensor components from the system. Rotor position detection is achieved through sensorless field-oriented control using mathematical algorithms based on stator current measurements, eliminating the need for multiple sensors, their mounting arrangements, and wire routing infrastructure.
Solution Approach 2:
The stator windings perform dual functions: generating electromagnetic torque and providing rotor position information through current measurements. This eliminates the need for separate sensor systems and their associated complexity.
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
This approach enables reliable cranking of the internal combustion engine without the need for sensors, reducing costs and space requirements, while improving the system's resilience to harsh conditions and wire damage.
Implementation Method 1
a rotor made of permanent magnets... For starting of IC engine, the electric machine is rotated which in turn rotates the crankshaft
Implementation Method 2
applying a pulse-width-modulated signal to the stator winding corresponding to determined initial position of the rotor
Data Source
AI summary
The invention relates to a method for cranking an internal combustion engine, including the steps of: (a) receiving a start signal; (b) determining an initial position of the rotor with respect to a stator phase winding; (c) applying a pulse-width-modulated signal to the stator winding corresponding to determined initial position of the rotor; (d) determining a threshold value of the stator current variation; (e) measuring current of the stator winding in response to applied pulse-width-modulated signal to determine current variation; (f) if current variation is more than the threshold value, determining updated rotor position, applying a pulse-width-modulated signal to the stator winding corresponding to the updated rotor position; and repeating steps (d)-(f); and (g) if current variation is less than the threshold value, applying a pulse-width-modulated signal to the stator winding corresponding to the last updated rotor position and repeating steps (d)-(g).