Electricity: power supply or regulation systems – For reactive power control – Using converter
Reexamination Certificate
2000-05-25
2001-01-23
Berhane, Adolf Deneke (Department: 2838)
Electricity: power supply or regulation systems
For reactive power control
Using converter
C323S285000
Reexamination Certificate
active
06177781
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a power-factor improvement device, and more particularly to such a power-factor improvement device, which greatly improves the power factor of the electric appliance at the load of AC power supply.
The electric appliances (for example, lighting fixtures, power equipment, air-conditioning systems, and etc.) at the loads have different power factor. The higher the power factor is, the higher the effective power value and the better the quality of the consumption of power supply will be. On the contrary, the lower the power factor is, the higher the consumption of wattless power and the poorer the quality of the consumption of power supply will be.
Nowadays, due to the upsurge of environmental protection concept and the fact that useful natural resources have become more and more less, we must use currently available resources in the best efficient way. “Power supply” is one of the requisite resources in our daily life. It is most urgent to provide a method of efficiently using the resource of power supply.
SUMMARY OF THE INVENTION
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a power factor improvement device, which greatly improves the power factor of the electric appliance at the load. It is another object of the present invention to provide a power factor improvement device, which automatically stabilizes the voltage, keeping the quality of power supply at the best condition. It is still another object of the present invention to provide a power factor improvement device, which automatically drops starting current to protect the electric appliance at the load. It is still another object of the present invention to provide a power factor improvement device, which meets environment protection requirements, enabling the resource of power supply to be consumed in the best efficient way. According to the present invention, the power factor improvement device is comprised of a voltage stabilizer unit, a current transformer, a voltage and current comparator circuit, an operand microprocessor, a power factor driver, a voltage regulator driver, a voltage detection circuit, a low voltage regulator, and a voltage drop rectifier circuit. The voltage stabilizer unit is coupled between the AC power supply input terminal and the load to adjust the voltage required for the electric appliance at the load. The current transformer is connected in series to the front end of the voltage stabilizer unit to detect the value of the current at the load, and to output detected current value data to the voltage and current comparator circuit for comparison. The voltage and current comparator circuit receives the current value data of the load from the current transformer, compares the current value data with the voltage waveform at two opposite ends of the voltage stabilizer unit, and outputs a parameter data subject to the result of the comparison. According to the preferred embodiment of the present invention, the voltage and current comparator circuit comprises a phase comparator, a current capacity adjuster for adjusting the minimum current value, a phase angle adjuster for adjusting the phase angle forwards or backwards, and a power factor adjuster for adjusting the value of the power factor of the electric appliance at the load. The operand microprocessor comprises at least one single-chip controlled to operate the parameter data of the voltage and current comparator circuit for obtaining the best power factor value, enabling the best power factor value to be further transmitted to the power factor driver. The power factor driver is for controlling capacitance's voltage throw-in and throw-off actions, comprising a plurality of control circuits, which are selectively driven by the best power factor value from the operand microprocessor to limit transient current thrown into capacitances at the initial stage, enabling the capacitances to adjust the power factor of the electric appliance at the load. The control circuits of the power factor driver each comprise a relay that is started through two starting stages, so that the service life of the capacitances can be greatly prolonged, the contact capacity of the electromagnetic contactors can be greatly reduced, and the electric appliance at the load can be well protected. The voltage regulator driver comprises a plurality of driving circuits for controlling the operation of the series of coils of the voltage stabilizer unit to keep the voltage of the power supply system stabilized. The voltage detection circuit comprises a voltage comparator controlled to detect the voltage level of the power supply system, and to drive the voltage regulator driver in adjusting the pre-set best voltage value for the electric appliance at the load. The low voltage regulator comprises a voltage stabilizer controlled to provide a stabilized DC power supply to the internal circuit. The voltage drop rectifier circuit provides a first voltage output which is a reference voltage for the voltage detection circuit, a second voltage output which is a driving voltage for the voltage regulator driver, and a third voltage output for the working of the low voltage regulator. Further, the operand microprocessor comprises an additional single-chip controlled to convert the data transmitted from the voltage and current comparator circuit into a digital code for driving a display unit, which is a seven-segment display that indicates the adjusted power factor of the AC power supply input terminal by means of percentage.
REFERENCES:
patent: 3801895 (1974-04-01), Kanngiesser
patent: 4555752 (1985-11-01), Kurosawa
patent: 4683529 (1987-07-01), Bucher II
patent: 5359276 (1994-10-01), Mammano
patent: 6037754 (2000-03-01), Harper
patent: 6104172 (2000-08-01), Josephs et al.
Bacon & Thomas PLLC
Berhane Adolf Deneke
Steve Yiua Shi Yin
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