Sensorless Starter Generator Control via Load Estimation
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Solution Overview
Problem
Conventional starter generator systems require position or speed sensors to control the starting process, which increases costs and power consumption, and are inefficient due to continuous rotation in a fixed arc before stopping.
Innovation Solution
A generator control apparatus that uses a speed open-loop control mode to drive the starter generator forward or reverse without sensors, by applying a drive current with specific frequency and amplitude to estimate load information and determine when to stop reverse rotation, thereby reducing starting time and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position or speed sensors are used to detect rotor position and speed, then the control precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the position and speed sensors from the control system. Instead of using sensors to detect rotor position and speed, the system uses sensorless control methods by monitoring the current and voltage signals already present in the system to estimate rotor position and speed, thereby reducing device complexity and cost while maintaining adequate control precision
Solution Approach 2:
The patent introduces an intermediary estimation mechanism that uses electrical signals (current and voltage) as mediators to infer mechanical state (rotor position and speed). The control system processes the relationship between applied voltage, resulting current, and motor parameters to calculate back-EMF and estimate rotor position and speed without direct mechanical sensors
2Reliability
If the starter generator continuously rotates in a fixed arc before stopping, then the starting position is ensured, but the starting time and power consumption increase
Solution Approach 1:
The patent applies dynamic adjustment to the rotation arc based on detected load conditions. Instead of a fixed rotation arc, the system dynamically adapts the rotation duration and arc length according to the actual engine load, allowing shorter rotation for light loads (reducing time and energy) while ensuring adequate rotation for heavy loads (maintaining reliability)
Solution Approach 2:
The patent changes the operational parameters (rotation arc, rotation time, current amplitude) based on detected load conditions. By monitoring current characteristics during the starting process, the system identifies load levels and adjusts subsequent rotation parameters accordingly, optimizing the balance between starting reliability and energy efficiency
3Reliability
If the starter generator operates with high power to cross compression top dead center, then the starting reliability is improved, but the power consumption increases
Solution Approach 1:
The patent applies partial action by providing high power only when necessary (during the critical compression top dead center crossing phase) rather than continuously. The system delivers excessive power temporarily during the high-load compression stroke to ensure reliable starting, then reduces power consumption during subsequent phases where full power is not needed
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 allows accurate load estimation without sensors, reducing starting time and power consumption, and avoiding unnecessary rotation, thus improving the efficiency of the starter generator system.
Implementation Method 1
The control module provides a PWM signal to the inverter so that the inverter converts the DC voltage into a drive voltage and a drive current to drive the starter generator
Implementation Method 2
the generator is used as an electric motor to drive the engine when the generator is stared
Data Source
AI summary
A method of starting an integrated starter generator drives a starter generator without using a rotor position sensor to start an engine. The method includes the following steps of: (a) applying a first drive current with a first frequency and a first amplitude to drive the starter generator to reversely rotate in a speed open-loop control mode, and acquiring a first load information according to a drive voltage and the first drive current of the starter generator, (b) confirming whether the first load information meets a heavy load condition, (c) stopping reversely rotating the starter generator when the first load information meets the heavy load condition, and (d) forwardly rotating the starter generator to drive the engine to start.