Modular Inverter Circuit for AC Supply and Cell Balancing
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Solution Overview
Problem
Existing power supply systems face challenges in efficiently supplying both primary loads with AC voltage and secondary loads with DC voltage, particularly in electric vehicles, due to battery cell variations and the need for complex circuits and high interference voltages, leading to inefficiencies and unreliable power distribution.
Innovation Solution
A circuit arrangement with configurable inverters and a control device that generates adjustable AC and DC voltages using modular inverters, allowing flexible power distribution to both primary and secondary loads, independent of the primary load's operating state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high clock frequencies are used to reduce voltage harmonics, then voltage quality is improved, but switching losses increase
Solution Approach 1:
The patent employs pulse width modulation (PWM) with periodic switching actions to generate AC voltages from DC battery voltage. By using periodic pulse sequences with varying widths rather than continuous high-frequency switching, the system achieves voltage synthesis with reduced switching losses while maintaining acceptable harmonic levels through controlled periodic action.
Solution Approach 2:
The patent changes the switching strategy by using variable pulse widths instead of fixed high-frequency switching. The pulse width modulation technique varies the duty cycle parameter to control output voltage amplitude, thereby reducing switching frequency and associated losses while still generating the required AC voltage waveform with acceptable harmonic content.
2Stability of the object's composition
If passive charge balancing is used to balance battery cells, then charge balancing is achieved, but valuable electrical energy is lost
Solution Approach 1:
The patent merges the charge balancing function with the main power conversion function by using the same inverter circuitry to both generate AC output voltage and perform cell balancing. The inverter switches are controlled to redirect current from fully charged cells to less charged cells during normal operation, combining two functions into one system and avoiding separate balancing circuits that would waste energy.
Solution Approach 2:
The battery management system performs charge balancing using the system's own inverter circuitry and control capabilities without requiring external balancing equipment. The control unit automatically identifies charged cells and redirects current through the inverter switches to balance charges, enabling the system to self-regulate and maintain charge balance without energy-wasting passive components.
3Loss of energy
If active charge balancing is used to resolve passive balancing problems, then charge balancing efficiency is improved, but circuit complexity increases
Solution Approach 1:
The inverter circuit serves multiple functions: it generates AC output voltage for the load, performs charge balancing between battery cells, and provides voltage conversion. By making the inverter universal and multi-functional, the patent achieves active charge balancing efficiency without adding separate dedicated balancing circuits, thereby avoiding increased overall system complexity.
Solution Approach 2:
The control unit continuously monitors the charge states of individual battery cells and uses this feedback information to dynamically adjust the inverter switching patterns. Based on real-time cell voltage measurements, the control system automatically implements active charge balancing by redirecting current from fully charged cells to less charged cells, achieving efficient balancing through intelligent control rather than complex hardware.
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
Ensures reliable power supply to both primary and secondary loads, including electric vehicles at low speeds or standstill, by reducing switching losses and enabling efficient charge balancing and voltage regulation.
Implementation Method 1
The level of the voltage pulses depends on the battery voltage UDC and is therefore constant. To generate AC voltages, the duration of the voltage pulses can be varied as an actuating element. It is usually calculated using the pulse width modulation (PWM) method.
Data Source
AI summary
A circuit arrangement for supplying electric-power to a primary consumer via a first operating AC voltage having a control device and at least one first inverter that has a first and second primary supply terminal between which the first operating AC voltage is present. The first inverter has a configurable first inverter module and a configurable second inverter module which jointly provide the first operating AC voltage. Provision is made for the first inverter to have a first secondary supply terminal arranged between the first inverter module and the second inverter module. The control device is designed to configure the inverter modules of the first inverter to provide a first secondary voltage between the first secondary supply terminal and one of the primary supply terminals to supply power to an auxiliary consumer. A supply voltage is generated by a rectifier from the secondary voltages.