DC/DC Converter Inductor Balancing for Dual Bus Capacitor Voltage
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Solution Overview
Problem
Conventional DC/DC converters with two bus capacitors face voltage imbalance due to different duty cycles of switches, necessitating additional balance circuits that increase circuit size and reduce power density.
Innovation Solution
A power converter and conversion method utilizing inherent inductor components to balance capacitor voltages, reducing overall circuit size and improving power density by transmitting electrical energy between capacitors and inductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a balance circuit is added to adjust bus capacitor voltages, then voltage balance is achieved, but circuit size increases and power density decreases
Solution Approach 1:
The patent merges the voltage balance function with the existing inductor components already present in the DC/DC converter circuit. Instead of adding a separate balance circuit, the inductors that are already part of the power conversion path are utilized to transfer energy between the positive and negative bus capacitors, thereby achieving voltage balance without increasing circuit size.
Solution Approach 2:
The inductor components in the converter are made multi-functional: they simultaneously perform their primary function of energy storage and transfer for voltage conversion, and an additional function of voltage balancing between the two bus capacitors. This is achieved by controlling the switches to enable energy transfer from one bus capacitor through the inductor to the other bus capacitor when voltage imbalance is detected.
2Stability of the object's composition
If a balance circuit is added to adjust bus capacitor voltages, then voltage balance is achieved, but power density decreases
Solution Approach 1:
The voltage balance function is merged into the existing power conversion path using the same inductor and switch components. This eliminates the need for additional dedicated balance circuitry that would increase overall circuit size and reduce power density.
Solution Approach 2:
The existing inductor and switch components perform dual functions: primary power conversion and voltage balancing. By making these components multi-functional, the patent avoids adding extra components that would reduce power density, while still achieving the required voltage balance between bus capacitors.
3Power
If different duty cycles are used for switches, then power conversion is achieved, but voltage imbalance between bus capacitors occurs
Solution Approach 1:
The patent implements a feedback control mechanism where the voltages of the positive and negative bus capacitors are monitored. When an imbalance is detected, the control system adjusts the switch duty cycles to enable energy transfer through the inductor from the capacitor with higher voltage to the one with lower voltage, thereby restoring voltage balance while maintaining the required power conversion function.
Solution Approach 2:
The voltage balancing operation is performed periodically based on voltage imbalance detection. The control system continuously monitors bus capacitor voltages and activates the balance function (through periodic energy transfer via the inductor) only when needed, allowing the system to maintain both power conversion and voltage balance without continuous intervention.
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
Achieves voltage balance and hybrid power supply while satisfying various load requirements, enhancing power density and efficiency without the need for additional balance circuits.
Implementation Method 1
the first inductor and the second inductor store or release energy, thereby transmitting electrical energy between the first bus capacitor, the second bus capacitor, the first load capacitor and the second load capacitor
Implementation Method 2
When the switch is in the on-state, the switch transmits the electrical energy from the bus capacitor to the inductor
Implementation Method 3
When the switch is in the off-state, the diode transmits the electrical energy from the inductor to the load capacitor
Data Source
AI summary
A power converter and a power conversion method are provided and capable of bus capacitor voltage balance based on inherent inductor components of the power converter. Compared with the conventional approach that adds a balance circuit, the power converter and the power conversion method can reduce a size of overall circuit and improve a power density. In addition, two relays of the power converter are configured to switch switching states such that two inductors store or release energy, thereby transmitting electrical energy between two bus capacitors and two load capacitors. The power converter and the power conversion method are able to realize energy balance and hybrid power supply and satisfy various load requirements.