Active Harmonic Suppression in DC Vehicle Controllers
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Solution Overview
Problem
Conventional methods for controlling DC vehicles fail to adequately suppress interference currents and harmonics in specific frequency ranges, leading to potential main circuit breaker openings and non-compliance with customer-defined harmonic amplitude limits, which affects vehicle availability and operational reliability.
Innovation Solution
A method and controller that actively control the main current by generating a manipulated current based on measured signals representing the main current, voltage, and DC-link voltage, using a control circuit with filters and compensators to directly suppress interference currents and harmonics in targeted frequency ranges, effectively eliminating them by setting the current signal to a reference value, such as zero.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conservative design of the input filter is used to attenuate interference currents, then compliance with harmonic amplitude limits is achieved, but the device complexity and cost increase
Solution Approach 1:
The invention changes the parameters of the system by introducing active control through the controller, which dynamically adjusts the main current to compensate for interference currents. This replaces the passive conservative filter design with an active control approach that achieves the same compliance goal with potentially simpler filtering requirements.
Solution Approach 2:
The controller acts as an intermediary between the main current and the interference currents. It measures the interference currents and actively controls the main current to counteract them, serving as a mediator that eliminates the need for oversized passive filters.
2Object-generated harmful factors
If damping is added to the DC-link with emulated damping admittance, then some attenuation of main current harmonics is achieved, but the attenuation is not sufficient to comply with gabarit requirements
Solution Approach 1:
The invention converts the harmful interference currents into a useful control signal. The controller measures the interference currents and uses them to generate the manipulated signal that actively counteracts the harmonics, turning the harmful factor into the basis for the control action.
Solution Approach 2:
The system implements feedback by continuously measuring the interference currents and using this information to adjust the main current through the controller. This closed-loop feedback mechanism ensures sufficient attenuation to meet gabarit requirements, overcoming the limitations of passive damping.
3Reliability
If multiple interference current violations occur in a short time, then the main circuit breaker opens, but this leads to vehicle unavailability and reduced productivity
Solution Approach 1:
The controller performs preliminary action by actively controlling the main current before interference current violations can accumulate and trigger the circuit breaker. It continuously monitors and compensates for harmonics, preventing the condition that would lead to breaker opening and vehicle shutdown.
Solution Approach 2:
The system provides beforehand cushioning by using the controller to buffer against interference current violations. The active control creates a cushion that absorbs the harmful effects of harmonics, preventing them from reaching levels that would cause circuit breaker tripping and vehicle unavailability.
Data Source
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AI summary
A Method and a controller for controlling a vehicle (20), e.g. a DC vehicle, are provided. The vehicle (20) comprises a current collector/pantograph (24) for receiving a main voltage (VL) and a corresponding main current (IL) from a main voltage provider (22), an input filter (25) connected to the current collector/pantograph (24) and containing a filter element (26) and a DC-link (28) for filtering the main current (IL) and the main voltage (VL) in order to provide a DC-link voltage (VD), at least one load (34) connected to the DC-link (28), and the controller being coupled to the current collector (24), the DC-link (28), and the load (34). The method comprises receiving a current signal (IS), which is representative for the main current (IL), receiving a main voltage signal (VMS), which is representative for the main voltage (VL), receiving a DC-link voltage signal (VDS), which is representative for the DC-link voltage (VD), determining a manipulated signal (MS) depending on the current signal (IS), the main voltage signal (VMS), and the DC-link voltage signal (VDS), and controlling at least the one load (34) such that the load (34) supplies a manipulated current (Implt) depending on the manipulated signal (MS) to the DC-link (28), wherein the manipulated signal (MS) is determined such that in a given frequency range the main current (IL) is controlled to a reference value by the manipulated current (Implt).