Variable Voltage Converter Inductor Capacitance Ripple Reduction
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Solution Overview
Problem
Existing variable voltage converters for electric drive systems in electrified vehicles require large capacitance and inductance to limit traction battery current ripple, leading to significant packaging space, cost, weight, and efficiency penalties, as well as cooling challenges.
Innovation Solution
The proposed solution involves a variable voltage converter configuration with a non-gapped inductor and series capacitor, where the inductance is proportional to the inverse of the product of capacitance and switching frequency squared, allowing for a T configuration of inductors and a shared terminal, which reduces the necessary inductance and capacitance values, thereby minimizing packaging space, cost, weight, and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large capacitance and inductance are used to limit traction battery current ripple, then current ripple is reduced, but packaging space, cost, weight, and cooling requirements increase significantly
Solution Approach 1:
The patent changes the operating parameters by using a high switching frequency (e.g., 20 kHz or higher) to enable the use of smaller inductance and capacitance values while maintaining effective current ripple limitation. This parameter change allows the converter to achieve the same ripple filtering performance with significantly reduced component sizes and weights.
2Reliability
If large capacitance and inductance are used to limit traction battery current ripple, then current ripple is reduced, but packaging space increases significantly
Solution Approach 1:
The patent employs high switching frequency operation to reduce the required inductance and capacitance values, directly shrinking the physical volume of the converter. The T-configuration with non-gapped inductors further optimizes space utilization by enabling more compact magnetic component design.
Solution Approach 2:
The patent merges multiple inductors into a T-configuration where inductors share common magnetic paths and physical space. The non-gapped inductor design allows for tighter integration and more efficient use of packaging volume compared to traditional gapped inductor configurations.
3Reliability
If large capacitance and inductance are used to limit traction battery current ripple, then current ripple is reduced, but cost increases significantly
Solution Approach 1:
The patent uses high switching frequency to reduce the required values of inductance and capacitance, which directly lowers the cost of these passive components. Smaller components not only reduce material costs but also decrease assembly complexity and overall manufacturing expenses.
4Reliability
If large capacitance and inductance are used to limit traction battery current ripple, then current ripple is reduced, but efficiency decreases and cooling challenges increase
Solution Approach 1:
The patent employs high switching frequency operation with optimized duty cycles to reduce the size of passive components while maintaining effective ripple filtering. The T-configuration with non-gapped inductors reduces magnetic losses and improves overall converter efficiency, thereby reducing energy losses and cooling requirements.
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 configuration effectively filters current ripple away from the traction battery, allowing for a smaller inductance to achieve voltage boost, resulting in a more compact, lightweight, efficient, and easier-to-cool variable voltage converter.
Implementation Method 1
The non-gapped inductor defines an inductance proportional to an inverse of a product of a capacitance of the capacitor and the switching frequency squared
Implementation Method 2
A battery pack is included in the electrified vehicles providing electricity to electric machines
Data Source
AI summary
A vehicle electric drive includes a battery, an inverter, and a power converter electrically between the battery and inverter. The power converter includes series switches activated at a predefined switching frequency, a series capacitor and non-gapped inductor, and an inductor electrically between the non-gapped inductor and series switches. The non-gapped inductor defines an inductance proportional to an inverse of a product of a capacitance of the capacitor and the switching frequency squared.