초록 ▼

A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure, and a thermal reservoir. The photovoltaic (PV)

A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure, and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

대표청구항 ▼

1. A solar powered apparatus which comprises:a variable speed motor; a power source which converts light into electrical power having a DC voltage; a power bus coupled to the power source and configured to provide electrical power at said DC voltage to the variable speed motor, and a controller coup

1. A solar powered apparatus which comprises:a variable speed motor; a power source which converts light into electrical power having a DC voltage; a power bus coupled to the power source and configured to provide electrical power at said DC voltage to the variable speed motor, and a controller coupled to the power bus to detect said DC voltage and coupled to the variable speed motor to provide a speed control signal, wherein the controller determines a time derivative of said DC voltage, wherein the controller increases the motor speed if the derivative of said DC voltage is above a predetermined threshold, and wherein the controller decreases the motor speed if the derivative of said DC voltage is below the predetermined threshold, and wherein the controller is further configured to adjust the speed control signal to maximize usage of the electrical power from the power source wherein the controller determines a second-order time derivative of said DC voltage, and wherein the controller increases the motor speed if the second-order derivative is above a predetermined threshold, and wherein the controller decreases the motor speed if the second-order derivative is below the predetermined threshold, wherein the controller is configured to adjust the speed control signal to maximize usage of the electrical power from the power source.