Hybrid Powertrain Controller Shaft Speed Regulation

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Solution Overview

Problem

Mobile working machines with hybrid powertrain topologies experience sharp speed drops due to the delayed response of internal combustion engines, which cannot be effectively mitigated by combining them with electric motors without communication for torque support.

Innovation Solution

A controller that dynamically switches between internal combustion engines and electric motors to regulate shaft speed based on power requirements, using a speed controller to select the most suitable power source for immediate response and prevent speed deviations, and a power management device to pre-control torque for optimal power distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an internal combustion engine is used as the main power source with PID speed control, then the engine can regulate speed through power output changes, but sharp speed drops occur because the engine only reacts after speed deviation is detected

Engineering Contradiction:
Improvespeed regulation stabilityVSAvoidshaft speed stability
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The control device performs preliminary action by having the electric motor proactively compensate for anticipated torque deficits before the internal combustion engine can react. When a speed deviation is detected, the electric motor immediately provides supporting torque to prevent sharp speed drops, rather than waiting for the combustion engine to respond. This preliminary intervention maintains speed stability throughout the transient period.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The electric motor serves as an intermediary between the internal combustion engine and the shaft, mediating torque delivery to smooth out speed fluctuations. The control device coordinates both power sources, allowing the electric motor to fill torque gaps and bridge the response time gap of the combustion engine, thereby preventing sharp speed changes while maintaining overall speed regulation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Power

If an electric motor is combined with an internal combustion engine for faster torque dynamics, then torque response improves, but speed changes cannot be prevented without a higher-level controller that coordinates torque contribution

Engineering Contradiction:
Improvetorque dynamicsVSAvoidcontroller structure
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The control device merges the control functions of the internal combustion engine and electric motor into a unified control system. Rather than using separate controllers or a complex higher-level coordinator, the invention integrates both power sources under a single control device that directly manages torque contribution from each source based on real-time shaft speed feedback, simplifying the overall controller structure while maintaining coordinated torque delivery.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The control device implements feedback control by continuously monitoring shaft speed and using this information to dynamically adjust the torque contribution of both the internal combustion engine and electric motor. The speed feedback loop enables the control device to determine the exact amount of torque support needed from the electric motor at any given moment, coordinating power delivery without requiring complex predictive algorithms or higher-level controllers.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If the internal combustion engine regulates speed by calculating required torque, then speed can be set to target values, but the engine cannot prevent sharp speed changes due to its inherent response delay

Engineering Contradiction:
Improvespeed control precisionVSAvoidengine response time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The electric motor performs preliminary action by providing immediate torque support when a speed deviation is detected, before the internal combustion engine can complete its torque adjustment. The control device calculates the required torque support and applies it proactively through the electric motor, compensating for the combustion engine's response delay and preventing sharp speed changes during the transient period.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the operational parameters of the hybrid powertrain by dynamically adjusting the torque contribution split between the internal combustion engine and electric motor. When speed regulation is needed, the control device shifts the parameter distribution to increase electric motor torque output, leveraging its faster response characteristics to弥补 the combustion engine's sluggishness while maintaining precise speed control.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3680138B1Control for a mobile work machine, control circuit, method and work machine
Publication Date: 2021.10.06 ROBERT BOSCH GMBH
  • EP3680138B1 patent drawingFigure 1
  • EP3680138B1 patent drawingFigure 2

AI summary

A control system for a mobile working machine with two main power components and at least one power component is disclosed. The main power components and the power component are connected via a rotating shaft for power exchange. Furthermore, the control system includes at least one speed controller, which regulates the speed of the rotating shaft and also regulates the speed via one of the main power components.