Phase Control Loop for Hybrid Generator Speed Regulation

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Solution Overview

Problem

Hybrid vehicles with internal combustion engines and electric generators experience torque ripples and vibrations due to the pulsating torque of the engine, leading to increased mechanical wear and current oscillations in the generator, particularly when the engine has a low flyweight.

Innovation Solution

A phase control loop is implemented to regulate the rotational speed of the electric generator, using a rotational speed signal from the drive shaft, determining amplitude and phase differences to generate a correction signal that subtracts ignition synchronous vibrations, thereby preventing torque ripples and reducing vibrations and current oscillations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the flyweight of the internal combustion engine is reduced or eliminated, then the system weight is decreased and the electrical machine can operate at lower rotational speeds, but the torque ripple of the drive shaft increases due to engine torque pulsating at ignition frequency

Engineering Contradiction:

Improveflyweight massVSAvoidtorque ripple

Core Design Contradiction:

Weight of moving objectVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback control system where the actual rotational speed of the generator is continuously measured and compared with a reference speed. The speed difference signal is processed through a phase-locked loop to generate corrective torque commands that are fed back to the electrical machine controller, dynamically compensating for torque ripples in real-time

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary control system consisting of a phase-locked loop and signal processing unit that mediates between the engine's pulsating torque and the generator's rotational speed requirements. This intermediary processes the speed difference signal and generates corrective torque commands, acting as a buffer that decouples the direct transmission of torque ripples from the generator

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the flyweight is reduced, then the system becomes more responsive and efficient, but vibrations of the internal combustion engine housing increase and current oscillations occur in the generator output current

Engineering Contradiction:

Improvesystem efficiencyVSAvoidvibrations and current oscillations

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful effect of engine torque pulsations into a useful control signal. By measuring the actual generator speed and comparing it with the reference speed, the system generates a speed difference signal that directly reflects the torque ripple characteristics. This signal is then processed to generate corrective torque commands that actively counteract the harmful vibrations and current oscillations, transforming the problem into a control opportunity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Device complexity

If a rigid drive shaft directly couples the internal combustion engine and electrical machine, then mechanical complexity is reduced, but torque ripples are transmitted directly causing increased mechanical wear and noise

Engineering Contradiction:

Improvedrive train structureVSAvoidmechanical wear and noise

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical function of a flexible or damped drive shaft with an electronic control system. Instead of using mechanical elements to attenuate torque ripples, the system uses electronic sensing of generator speed, signal processing through a phase-locked loop, and electronic control of the electrical machine torque to achieve ripple suppression, thereby eliminating the need for complex mechanical damping structures

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10033315B2Phase control loop, generator control device and method for activating an electric drive system of a hybrid vehicle

Publication Date: 2018.07.24 ROBERT BOSCH GMBH

AI summary

The invention relates to a phase control loop for the rotational speed regulation of an electric generator fed by an internal combustion engine, having an input connection, which is designed to receive a rotational speed signal measured on a drive shaft of the electric generator, an amplitude determination device, which is coupled to the input connection and which is designed to determine the amplitude of rotational speed ripples of the measured rotational speed signal, a correction function device, which is coupled to the amplitude determination device and the input connection and which is designed to determine a rotational speed correction signal on the basis of the determined amplitude of the rotational speed ripple and of the measure rotational speed signal, a phase discriminator, which is coupled to the amplitude determination device and the correction function device and which is designed to determine a phase difference signal between the measured rotational speed signal and the rotational speed correction signal, wherein the correction function device is designed to regulate the rotational speed correction signal on the basis of the determined phase difference signal to a phase difference of zero, and a summing element, which is designed to subtract the rotational speed correction signal from the measured rotational speed signal and to provide a corrected rotational speed signal to an output connection of the phase control loop.