DC Bus Power System with PV Pre-conditioner
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Solution Overview
Problem
Existing electrical power systems are inefficient in utilizing direct current (DC) power from photo-voltaic cells due to conversion losses from AC to DC and back, especially when the power source is unstable, such as solar power, which varies with sunlight availability.
Innovation Solution
A DC electrical system with multiple inputs and outputs, utilizing a DC/DC pre-conditioner to maintain the photo-voltaic power source at its maximum power point, connecting it directly to a DC bus, and using AC/DC converters to supplement power from the AC grid or battery, minimizing conversion losses and storing surplus energy in a battery for later use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If photo-voltaic power is converted to AC and then back to DC, then the power can be integrated with AC grid infrastructure, but significant power conversion losses occur (about 60% due to DC/AC inversion and 40% due to DC/DC loss)
Solution Approach 1:
The invention extracts the photo-voltaic power source directly from the unstable solar input and connects it through a DC/DC pre-conditioner directly to the DC bus, bypassing the AC conversion pathway entirely. This extraction of the PV source from the AC conversion chain eliminates the 60% DC/AC inversion loss while maintaining grid compatibility through the DC bus architecture.
Solution Approach 2:
The DC/DC pre-conditioner serves as an intermediary device between the unstable photo-voltaic source and the DC bus. It conditions the unstable DC output from PV panels into stable DC suitable for the bus, eliminating the need for AC conversion while maintaining system compatibility. This intermediary approach reduces total conversion losses significantly.
2Loss of energy
If photo-voltaic power is used directly without conversion, then conversion losses are minimized, but the unstable output from solar panels cannot reliably power devices requiring stable voltage
Solution Approach 1:
The DC/DC pre-conditioner acts as an intermediary that accepts unstable DC from photo-voltaic panels and outputs stable DC to the bus. This mediator device performs voltage regulation and stabilization while maintaining the DC form factor, thus minimizing conversion losses while ensuring voltage stability for connected devices.
Solution Approach 2:
The DC/DC pre-conditioner changes the electrical parameters of the photo-voltaic output by regulating voltage and current to maintain stable operation. It adjusts the DC parameters dynamically to keep the output stable despite variations in solar irradiance, thereby resolving the stability issue without requiring AC conversion.
3Reliability
If AC to DC conversion is used to power DC devices, then reliable power delivery is achieved, but conversion efficiency is reduced due to transformer losses
Solution Approach 1:
The invention extracts the power delivery pathway from the traditional AC conversion route and creates a direct DC pathway from the DC bus to DC devices. This eliminates the transformer-based AC/DC conversion step, removing associated losses while maintaining reliable power delivery through the stable DC bus voltage.
Solution Approach 2:
The DC bus provides continuous stable voltage to DC devices without the interruptions and losses associated with AC conversion cycles. The continuous DC action maintains reliable power delivery while eliminating the energy losses inherent in transformer-based AC to DC conversion processes.
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 significantly reduces power conversion losses, ensuring that a majority of the load is powered efficiently by the photo-voltaic source during peak hours, with minimal reliance on AC grid power, and effectively manages energy storage and retrieval to maintain system stability.
Implementation Method 1
A photo-voltaic power source outputs (DC) is connected to the bus through a DC/DC pre-conditioner
Data Source
AI summary
A direct current electrical power system having AC grid power attached to the bus through AC/DC converter, PV panel attached to the bus through DC/DC pre-conditioner, a first direct current load attached directly to the bus, and a second direct current load attached to the bus through a DC/DC converter. The function of the AC grid and AC/DC converter is to create and regulate the DC bus voltage. The function of the PV power is to provide as much power as required to the DC loads. Since the conversion efficiency of the DC/DC pre-conditioner is much higher than that of the AC/DC converter, the conversion loss is greatly reduced if the load is mainly powered from PV instead of AC grid. In addition, a battery can be attached to the bus through a battery charger/controller, which is a bi-directional DC/DC converter.