Dynamic Intermediate Circuit Capacitance for Voltage Ripple Compensation
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Solution Overview
Problem
The existing intermediate circuit capacitance in on-board automobile energy systems is large, costly, and heavy due to the need for high dielectric strength to handle high voltages, which leads to increased size and weight, and struggles to effectively compensate for voltage ripples caused by inverters.
Innovation Solution
A dynamic enlargement of the intermediate circuit capacitor using active circuitry that detects voltage changes via high-pass or band-pass filters and compensates by feeding energy into or removing it from the circuit, allowing for a smaller capacitance while maintaining effective voltage ripple compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large intermediate circuit capacitance is used to handle high voltages with high dielectric strength, then voltage ripple compensation is effective, but the size, weight, and cost of the capacitor increase significantly
Solution Approach 1:
The patent applies dynamics by making the capacitance value adjustable rather than fixed. The intermediate circuit capacitance is divided into a first capacitance and a second capacitance that can be dynamically switched between different connection states (series, parallel, or individual connections) based on the operating conditions and voltage ripple characteristics, allowing the effective capacitance to adapt to different scenarios
Solution Approach 2:
The patent changes the electrical parameters of the intermediate circuit by switching between different capacitance configurations. The connection state of the first and second capacitances is changed based on detected voltage ripple characteristics, thereby dynamically adjusting the effective capacitance value and impedance to optimize voltage ripple compensation under different operating conditions
2Reliability
If a large intermediate circuit capacitance is used to handle high voltages, then voltage ripple compensation is effective, but the cost and size of the component increase
Solution Approach 1:
The patent segments the intermediate circuit capacitance into multiple independent capacitance elements (first capacitance and second capacitance) that can be connected in different configurations. This segmentation allows the use of smaller, more cost-effective capacitors with lower individual voltage ratings, while still achieving the required overall capacitance and voltage ripple compensation performance through strategic series and parallel connections
Solution Approach 2:
The patent makes the capacitance configuration dynamic by using switching elements to reconfigure the connection states of the segmented capacitances based on operating conditions. This dynamic reconfiguration allows the system to achieve effective voltage ripple compensation with smaller, cheaper capacitors rather than requiring a single large, expensive high-voltage capacitor
3Device complexity
If a fixed capacitance value is used in the intermediate circuit, then the circuit is simple, but it cannot effectively adapt to varying voltage ripple conditions
Solution Approach 1:
The patent introduces dynamics into the intermediate circuit by implementing switching mechanisms that can change the connection configuration of the capacitance elements based on detected voltage ripple characteristics. This allows the circuit to adapt its effective capacitance value to different operating conditions while maintaining a relatively simple overall structure
Solution Approach 2:
The patent implements feedback by detecting the characteristics of voltage ripples in the intermediate circuit and using this information to control the switching of capacitance connection states. The detection unit monitors voltage ripple characteristics and provides feedback to the switching control, which adjusts the capacitance configuration to optimally compensate for the detected ripple conditions
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 the size, weight, and cost of the capacitance while providing better voltage ripple compensation, particularly by predicting and compensating for periodic components of the switching signal, resulting in a more economical and efficient solution.
Implementation Method 1
This can be done, for example, via a high-pass or band-pass filter in order to separate the unwanted voltage ripple components from the high-voltage signal
Implementation Method 2
This can be done, for example, via a high-pass or band-pass filter in order to separate the unwanted voltage ripple components from the high-voltage signal
Implementation Method 3
An intermediate circuit capacitance C0 is connected in parallel with the input of the inverter 203 and the battery 200. The intermediate circuit capacitor C0 has the task of attenuating the alternating-voltage components caused by the inverter
Implementation Method 4
electric energy for compensating for the change in the capacitance is fed in in dependence on the change in the electrical quantity
Data Source
AI summary
The disclosure relates to a method and a circuit for the improved use of a capacitance in an intermediate circuit. According to the disclosure, a change in a voltage in an intermediate circuit is detected and electrical energy is actively provided depending on the change in the electrical variable in order to compensate the change. According to the disclosure, a capacitance used in the intermediate circuit can end up significantly smaller if the electrical energy fed in is used, in that the voltage of the capacitance is supported by a current fed into the capacitance on the earth side.