Title: Electronic power-saving power control circuit
Abstract: An electronic power-saving power control circuit for connection between a single-phase power supply and a lighting fixture to control the output of power supply to the lighting fixture is disclosed to include a CPU (central processing unit), a power voltage detector, a silicon controlled semiconductor circuit, a current phase detector, a trigger circuit, a resistor, a current detector, and a DC power supply circuit. The electronic power-saving power control circuit saves the consumption of power supply by dropping the voltage without affecting normal working of the lighting fixture at the load and, achieves an overcurrent protection.
Patent Number: 6,982,858 Issued on 01/03/2006 to Shih
| Inventors:
|
Shih; Te-Fu (Taichung, TW)
|
| Assignee:
|
Digitek Technology Co., Ltd. (Taipei Hsien, TW)
|
| Appl. No.:
|
424805 |
| Filed:
|
April 29, 2003 |
| Current U.S. Class: |
361/93.1; 323/905 |
| Current Intern'l Class: |
H02H 3/00 (20060101) |
| Field of Search: |
361/931
323/237,905
|
References Cited [Referenced By]
U.S. Patent Documents
| 5327048 | Jul., 1994 | Troy.
| |
| 5583423 | Dec., 1996 | Bangerter.
| |
| 6175220 | Jan., 2001 | Billig et al.
| |
| 6191563 | Feb., 2001 | Bangerter.
| |
| 2001/0030514 | Oct., 2001 | Takahashi et al.
| |
| 2004/0002792 | Jan., 2004 | Hoffknecht.
| |
Primary Examiner: Leja; Ronald
Attorney, Agent or Firm: Rosenberg, Klein & Lee
Claims
What the invention claimed is:
1. Art electronic power-saving power control circuit connected between a single-phase
power supply and a lighting fixture for controlling the output of power supplied
to the lighting fixture, comprised of a CPU (central processing unit), a power
voltage detector, a silicon controlled semiconductor circuit, a current phase detector,
a trigger circuit, a resistor, a current detector, and a DC power supply circuit, wherein:
said CPU is a control center of the power-saving power control circuit, and adapted
to turn on said silicon controlled semiconductor circuit responsive to a triggering
angle required for a predetermined voltage drop and a time in which an electric
current detected by said current phase detector is zeroed when a power voltage
from said power voltage detector is received, causing said silicon controlled semiconductor
circuit to provide a power output to said lighting fixture, said CPU controlling
said silicon controlled semiconductor circuit to first provide a full operating
voltage to said lighting fixture for a time period established to ensure initiation
thereof and then gradually reduce the operating voltage to avoid a sharp change
in light output of said lighting fixture;
said voltage detector detects a voltage level of said single-phase power supply,
providing a detection result to said CPU;
said silicon controlled semiconductor circuit is a circuit formed of a silicon
controlled semiconductor and a protection circuit and connected in series between
said single-phase power supply and said lighting fixture for working with said
current phase detector and said trigger circuit to control power output to said
lighting fixture;
said current phase detector detects the time where the electric current passing
through said silicon controlled semiconductor is zeroed, and provides detection
information to said CPU for triggering said silicon controlled semiconductor;
said trigger circuit is adapted to trigger said silicon controlled semiconductor
circuit for output of power to said lighting fixture responsive to control by said CPU;
said resistor is electrically connected between said single-phase power supply
and said lighting fixture, and adapted to cause a voltage drop responsive to passage
of a load current therethrough;
said current detection circuit detects the value of a voltage drop across said
resistor and provides a corresponding measured current value to said CPU.
2. The electronic power-saving power control circuit as claimed in claim 1, the
relationship between said triggering angle and said voltage drop is not a linearity.
3. The electronic power-saving power control circuit as claimed in claim 1, wherein
said triggering angle and said voltage drop are defined within a limited range
subject to the nominal voltage and the features of said lighting fixture.
4. The electronic power-saving power control circuit as claimed in claim 1, wherein
said current detection circuit detects the level of the electric current subject
to the voltage drop at said resistor, so that said CPU drives said silicon controlled
semiconductor circuit to stop power supply from said lighting fixture when the
level of the electric current detected by said current detection circuit surpassed
the nominal current, achieving an overcurrent protection.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power-saving power control circuit for use
to control the output of power supply to a lighting fixture and, more particularly,
to an electronic power-saving power control circuit, which saves the consumption
of power supply by dropping the voltage without affecting normal working of the
lighting fixture at the load.
2. Description of the Related Art
Because the load of a lighting fixture, for example, a fluorescent lamp,
is fixed, the design and installation of a lighting fixture are done subject to
the nominal voltage of the power system, allowing the lighting fixture to function
normally within a tolerance about ±5˜10% of the nominal voltage. The
installation and brightness of a lighting fixture must be set subject to the voltage
level below the nominal voltage but higher than the lowest level of the tolerance.
The power consumption of an inductance ballast fluorescent lamp or the like has
a direct concern with voltage level. The higher the voltage is the greater the
consumption will be. Therefore, reducing the voltage to a lever closer to the lower
limit of the tolerance greatly saves power consumption without affecting normal
functioning of the load.
Various power-saving voltage stabilizers have been disclosed. These voltage
stabilizers commonly use a voltage regulator to increase or reduce voltage, providing
a stable voltage output to the load. However, these conventional designs are still
not satisfactory in function because of the following drawbacks.
1. In order to fit high current, the voltage regulator is heavy, bulky and
expensive, not economic for a small power system. Further, it is difficult to regulate
the voltage to a suitable range. Excessive high drop of voltage causes the equipment
at the load not able to function normally. Insufficient drop of voltage cannot
achieve a significant saving of power consumption.
2. The voltage regulators of conventional power-saving voltage stabilizers
cannot automatically and freely regulate voltage dropping. They drop the voltage
step by step. The range between two steps may be too far, resulting in an unstable
functioning of the load or insignificant saving of power consumption.
3. These conventional power-saving voltage stabilizers do not fit all equipment.
Further, power-saving designs using silicon controlled semiconductor to
control output power to motor drives are well known. It is known that a motor drive
consumes much energy than desired when the load is low. Using a silicon controlled
semiconductor to control output power saves much energy. The saving of energy may
be achieved by two methods, i.e., the variable voltage dropping and the fixed voltage
dropping. According to the variable voltage dropping method, the dropping of output
power and the range of energy saving vary with the change of the load, i.e., the
output voltage varies with the voltage of power source and the load. According
to the fixed voltage dropping method, the dropping of voltage is fixed subject
to fixed input power voltage and fixed load, i.e., the output voltage varies with
the input voltage. These two methods cannot be employed to lighting fixtures.
SUMMARY OF THE INVENTION
The present invention has been accomplished under the circumstances in view.
According to one aspect of the present invention, the electronic power-saving power
control circuit is connected between a single-phase power supply and a lighting
fixture for controlling the output of power supply to the lighting fixture, comprised
of a CPU (central processing unit), a power voltage detector, a silicon controlled
semiconductor circuit, a current phase detector, a trigger circuit, a resistor,
a current detector, and a DC power supply circuit. According to another aspect
of the present invention, the electronic power-saving power control circuit obtains
the necessary working voltage from the power supply connected to the lighting fixture,
therefore no independent power supply is necessary for the electronic power-saving
power control circuit. According to still another aspect of the present invention,
the relationship between the triggering angle and the voltage drop is not linearity.
According to still another aspect of the present invention, the triggering angle
(voltage drop) is defined within a limited range subject to the nominal voltage
and the features of the lighting fixture. According to still another aspect of
the present invention, the current detection circuit detects the level of the electric
current subject to the voltage drop at the resistor, so that the CPU drives the
silicon controlled semiconductor circuit to stop power supply from the lighting
fixture when the level of the electric current detected by the current detection
circuit surpassed the nominal current, achieving an overcurrent protection.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit block diagram of the present invention.
FIG. 2 is a detailed circuit diagram of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2, an electronic power-saving power control circuit
is designed to be connected between a single-phase power supply and a lighting
fixture, comprised of a CPU
10, a power voltage detector
20, a silicon
controlled semiconductor circuit
30, a current phase detector
40,
a trigger circuit
50, a resistor
60, a current detector
70,
and a DC power supply circuit
80.
The CPU
10 is the control center of the power-saving power control circuit.
When received power voltage obtained by the power voltage detector
20, the
CPU
10 electrically connects the silicon controlled semiconductor circuit
30 subject to the triggering angle required for the predetermined voltage
drop and the time in which the current detected by the current phase detector
40
is zeroed, producing a power output.
The voltage detector
20 detects the voltage level of power supply, providing
the information of detection result to the CPU
10.
The silicon controlled semiconductor circuit
30 is a circuit formed of
a silicon controlled semiconductor and a protection circuit and connected in series
between the single-phase power supply and the lighting fixture for working with
the current phase detector
40 and the trigger circuit
50 to control
power output.
The current phase detector
40 detects the time where the electric current
passing through the silicon controlled semiconductor is zeroed, and provides the
detection information to the CPU
10 for triggering the silicon controlled semiconductor.
The trigger circuit
50 is adapted to trigger the silicon controlled semiconductor
circuit
30 for output of power supply subject to the control of the CPU
10.
The resistor
60 is electrically connected between the single-phase power
supply and the lighting fixture, and adapted to cause a voltage drop upon passing
of the electric current.
The current detection circuit
70 detects the value of the electric current
passing through the resistor
60 subject to the voltage drop at the resistor
60 and, provides the measured current value to the CPU
10.
The DC power supply circuit
80 provides the whole circuit assembly with
the necessary DC power.
The operation of the present invention is outlined hereinafter. When power supply
turned on, the electronic power-saving power control circuit provides a full-voltage
power output to the lighting fixture, causing the lighting fixture to be started.
The electronic power-saving power control circuit runs a predetermined time delay
for enabling the lighting fixture to be completely started before power saving
function. Because the voltage at the load is reducing gradually only after the
lighting fixture has been completely started (after the aforesaid predetermined
time delay), the variation of brightness of the lighting fixture is not sharp.
When the lighting fixture completely started, the voltage detector
20 detects
the voltage level of power supply and then provides the information of detection
result to the CPU
10, enabling the CPU
10 to turn on the silicon
controlled semiconductor circuit
30 subject to the triggering angle required
for the predetermined voltage drop and the time in which the current detected by
the current phase detector
40 is zeroed, so that the silicon controlled
semiconductor circuit
30 provides a suitable voltage output to the lighting fixture.
The design of the triggering software of the CPU must consider two factors. One
factor is that there is no linearity between the range of voltage drop and the
triggering angle. The other factor is that the maximum voltage drop must be defined
so that the stability of the lightening of the lighting fixture can be maintained.
In addition to maintaining the stability of the lightening of the lighting fixture,
the current detection circuit detects the level of the electric current subject
to the voltage drop at the resistor, so that the CPU drives the silicon controlled
semiconductor circuit to stop power supply from the lighting fixture when the level
of the electric current detected by the current detection circuit surpassed the
nominal current, achieving an overcurrent protection.
A prototype of electronic power-saving power control circuit has been constructed
with the features of the annexed drawings of FIGS. 1 and 2. The electronic power-saving
power control circuit functions smoothly to provide all of the features discussed earlier.
Although a particular embodiment of the invention has been described in
detail for purposes of illustration, various modifications and enhancements may
be made without departing from the spirit and scope of the invention. Accordingly,
the invention is not to be limited except as by the appended claims.
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