Fuel Cell Injection Current Control via PWM Feedback
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Solution Overview
Problem
Conventional fuel cell stack diagnosis methods using decoupling capacitors to inject alternating current suffer from distortion issues at low frequencies, leading to increased costs and volume due to the need for large capacitors.
Innovation Solution
A closed-loop control system that injects alternating current without using a decoupling capacitor, utilizing a first converter to boost direct current from a vehicle battery, a second converter to convert it to alternating current, and a filter to ensure the current is not distorted, with a control unit adjusting the amplitude based on actual current feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a decoupling capacitor is used to inject alternating current into the fuel cell stack, then the current can be injected, but the capacitor causes distortion at low frequencies and increases cost and volume
Solution Approach 1:
The patent removes the decoupling capacitor from the system entirely and replaces it with a closed-loop control mechanism. The control unit directly generates alternating current by modulating the PWM duty cycle based on feedback from the actual current sensor, eliminating the need for large capacitors that caused volume and cost issues.
Solution Approach 2:
The patent implements a closed-loop control system where the control unit receives feedback about the actual alternating current injected into the fuel cell stack. Based on this feedback, the control unit adjusts the PWM duty cycle to maintain accurate current injection without distortion, replacing the passive capacitor-based approach with an active feedback-controlled approach.
2Reliability
If a decoupling capacitor is used to inject alternating current into the fuel cell stack, then the current can be injected, but the capacitor causes distortion at low frequencies and increases cost
Solution Approach 1:
The patent removes the decoupling capacitor from the system entirely and replaces it with a closed-loop control mechanism. The control unit directly generates alternating current by modulating the PWM duty cycle based on feedback from the actual current sensor, eliminating the need for large capacitors that caused volume and cost issues.
Solution Approach 2:
The patent implements a closed-loop control system where the control unit receives feedback about the actual alternating current injected into the fuel cell stack. Based on this feedback, the control unit adjusts the PWM duty cycle to maintain accurate current injection without distortion, replacing the passive capacitor-based approach with an active feedback-controlled approach.
3Ease of operation
If a decoupling capacitor is used to inject alternating current into the fuel cell stack, then the current can be injected, but distortion occurs at low frequencies
Solution Approach 1:
The patent implements a closed-loop control system where the control unit receives feedback about the actual alternating current injected into the fuel cell stack. Based on this feedback, the control unit adjusts the PWM duty cycle to maintain accurate current injection without distortion, replacing the passive capacitor-based approach with an active feedback-controlled approach.
Solution Approach 2:
The patent uses dynamic PWM duty cycle adjustment based on real-time feedback to maintain accurate current waveform injection across different frequencies. The system adapts its control parameters dynamically rather than relying on fixed capacitor characteristics that cause distortion at low frequencies.
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 reduces part costs and volume by eliminating the need for decoupling capacitors while ensuring undistorted alternating current injection into the fuel cell stack, enhancing diagnostic accuracy and efficiency.
Implementation Method 1
a first converter configured to convert direct current of a voltage corresponding to a battery for a vehicle, into direct current of a predetermined voltage
Implementation Method 2
a second converter configured to convert the converted direct current into alternating current
Data Source
AI summary
An apparatus for generating injection current for a fuel cell stack includes a first converter configured to convert direct current of a voltage corresponding to a battery for a vehicle, into direct current of a predetermined voltage; a second converter configured to convert the converted direct current into alternating current; a filter configured to filter a signal of a predetermined frequency band from the converted alternating current; and a control unit configured to perform a feedback control to allow the filtered alternating current to be injected without being distorted when injecting the filtered alternating current into the fuel cell stack.