GB2144932A - Programmable AC power line converter - Google Patents
Programmable AC power line converter Download PDFInfo
- Publication number
- GB2144932A GB2144932A GB08419506A GB8419506A GB2144932A GB 2144932 A GB2144932 A GB 2144932A GB 08419506 A GB08419506 A GB 08419506A GB 8419506 A GB8419506 A GB 8419506A GB 2144932 A GB2144932 A GB 2144932A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cycles
- power
- appliance
- alternating current
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
- H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
- H02M5/22—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M5/25—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
- H02M5/257—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
- H02M5/2573—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only with control circuit
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Ac-Ac Conversion (AREA)
Abstract
A device and method for averaging AC power to permit operation of an appliance on a power line having a voltage substantially higher than the design operating voltage of the appliance. A counter (IC1) counts a predetermined number of cycles of line power and resets. A control signal is emitted during only one of the cycles during each counting period. Switching means (Q1, IC2) are operative in response to the control signal to permit line power to be applied to the load only during the one cycle. The switching means employs light emitting (D2) and detecting devices for isolating the control signal from the line power applied to the appliance. <IMAGE>
Description
SPECIFICATION
Programmable AC power line converter
In field service, it is often desired to operate an appliance such as the household washing machine, clothes dryer, dishwasher or range burner ignitor on an alternating current power line having a RMS voltage of at least twice the intended operating voltage of the appliance. For example, in this country, many household appliances are designed to operate on power lines having a RMS voltage in the range of 110-120 volts AC; whereas, the residence is usually also supplied with line voltage in the range 220-240 volts AC.Often it is desirable to operate an appliance rated for 110 volt operation on 240 volts line power in order to minimize current draw where the appliance has a substantial power consumption and particularly where current in excess of 10 amps will be drawn on the 110 volt line.
Previously, where an appliance was to be operated on a power line having a voltage more than twice the rated operating voltage of the appliance, techniques were employed to cut out the power for a portion of each power line voltage cycle, which although reached higher than rated peak voltage, was applied for sufficiently short time such that the average current flow provided power at the rated level for appliance operation. However, such techniques for fractionalizing in the duty cycle of the power lines required complicated and costly electrical or electronic switching circuitry.
An example of such techniques is shown and described in the publication of Radio
Corporation of America, Camden, New Jersey entitled Applications Notes AN3697 (June, 1 968) and AN-3778 (August, 1 968); see also
General Electric applications note 200.53 (1 970), a publication of the General Electric
Company, Schenectady, New York.
Such known devices have typically employed a triac or SCR which conducts the low current for only a portion of the full cycle of the supply line voltage. Such devices must therefore have a power handling capability equivalent of the appliance being operated.
Providing such partial duty cycle switching at relatively high power levels has resulted in high cost for the solid state electronic switching devices employed in this type of power supply. Accordingly, it has long been desired to provide a way or means of averaging the power from a high voltage alternating current supply line for operation of an appliance rated for a voltage substantially less than the supply line voltage and yet provides such operation with low cost easy-to-manufacture and reliable current switching techniques.
The present invention provides power line averaging of an alternating current power supply by permitting the power line to conduct current to the load only a fractional number of successive continuous cycles of the power line voltage.
It will be observed that the power required for operation of an appliance having a load resistance R is proportional to V2/R where R is the load resistance and V is the line voltage.
It will be observed that if the line voltage is doubled the power available is four times the amount required. Therefore, where it is desired to deliver the same power required when operating on a line voltage twice that of the rated appliance, the circuit need conduct current to the appliance at an average of 1/4 or 25% of the time. This may be accomplished by conducting current to the appliance or load for one full cycle of operation out of each four successive cycles available.
The present invention is a control device for averaging alternating current electrical power in a load comprising counting means operable to count the successive cycles of an alternating current source, said counting means being operable to reset upon counting a predetermined number of cycles and to emit a signal during only the first of said number of counted cycles, series circuit means connecting said load to an alternating current source, and switch means connected to said series circuit means operative in response to said signal to conduct alternating current power to said load for only one of said counted cycles.
Embodiments of the present invention utilize a counter and a zero crossing detector with "AND" logic to enable the gate of a triac for conducting load current from the supply line only when a signal is received from the counter and when the line voltage crosses zero in a positive going direction. The counter emits a signal to the "AND" logic only during one of the successive cycles of a predetermined number of line voltage cycles. The zero crossing detector is optically isolated from the load current switching devices to reduce hazard of stray current.
The novel power averaging technique of embodiments of the present invention thus enables the power load switching device to be operational for only a fraction of the overall number of line voltage duty cycles. Thus, the power rating of the load switching device need be no greater than that of the appliance irrespective of the higher line voltage to which the appliance is connected.
The present invention is also a method of operating an electrical appliance with an alternating current power source having a line voltage substantially greater than the intended operating voltage of the appliance comprising the steps of counting a desired number of successive cycles of passing line voltage, resetting the counter after passage of said predetermined number, providing a control signal during only one of said number of cycles during each counting period, and detecting said control signal and switching line power "on" to said appliance for said one cycle, for providing power thereto for only one of said cycles during said counting period.
An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a schematic of the AC power converter of the present invention as connected to an electrical resistance heated fuel gas ignition system;
Figure 2 is an enlarged schematic of the integrated circuit portion of Fig. 1;
Figure 3A is timing diagram of the counter output signal of the circuit of Fig. 1;
Figure 3B is a graph of the voltage wave form at the base of Q5 of the circuit of Fig. 1;
Figure 3C is a timing diagram of the pulses on the collector of device Q5 of Fig. 1;
Figure 3D is a timing diagram of the pulses existing at the output of device Q6 of Fig. 1; and
Figure 3Eis a diagram of the voltage wave form at the output of device Q3 of Fig. 1.
Referring now to Fig. 1, the AC power converter of the present invention, indicated generally at 10, has one side of a power line connected via connector H1 to junction 1 2 which is connected via lead 14 to junction 1 6 which is connected in parallel with resistors
R1, R6 and in series with resistor R2.
Resistors R, R6 are connected to junction 1 8 which is connected to the positive lead of a diode D1 with the negative side of the diode connected to junction 20. Junction 20 is connected through capacitor C1 to ground and also via lead 21 to the collector of switching device Q1. Junction 20 is also connected to the power supply terminal 16 of counter IC1.
The clock input terminal 14 of IC1 is series connected through resistor R2 to junction 1 9.
The base of switching device Q1 is connected through resistor R3, to the first output register QO of IC1 at terminal 2 thereof. The fourth output register Q4 of IC1 is connected to terminal 1 5 thereof for resetting upon receipt of an output signal from Q4.
In the preferred practice of the invention,
IC1 is an octal counter which continues sequencing its output at clock frequency until an output at register Q4 provides a reset pulse which restarts the counting sequence.
The emitter of switch Q1 is connected via
lead 22 to junction terminal 1 of integrated circuit device IC2.
Junction 12 on the power line H1 is con
nected through resistor R4 to junction 24 which is connected via lead 26 to terminal 4
of an integrated circuit shown in dashed out
line as IC2. Junction 24 is also connected to the gate of a triac switching device Q2 which
has the input thereof connected to junction 1 2 and the output terminal connected to junction 28. In the presently preferred practice, the switching device Q2 is chosen so as to be capable of carrying the power of the appliance load.
Junction 28 is also connected through-resistor R5 to terminal 6 of IC2. Junction 28 is also connected to connector terminal L2 of the power line for connection to appliance load.
Referring now to Fig. 2, the integrated circuit IC2 is shown in enlarged schematic detail wherein terminal 1 thereof is connected to the positive terminal of a light emitting diode (LED) D2 with the negative terminal thereof connected through output terminal 2 to ground.
iC2 includes a photo-sensitive solid state switching device Q4 having the emitter thereof connected to one input of AND switch Q6, with the remaining input of Q6 connected to junction 30. Junction 30 is also connected to a source of positive voltage and to the collector of switching device 05. Q5 has the base thereof connected to the positive junction 32 of a diode bridge network indicated generally at 34. The opposite negative junction 36 of diode network 34 is connected to the emitter of switching device Q5.
The diode network 34 comprises diode D5,
D6, D7 and D8. The junction 38 which con
nects diode D5 and D6 is connected via lead 40 to junction 42 which is connected to output terminal 4 of IC2. The remaining opposite bridge junction 44 is connected via lead
46 to junction 48, which also connects to
output terminal 6 of IC2. Diode bridge 34 thus provides full wave rectification of line
power to switching device Q5.
The output of AND device Q6 is applied via
lead 50 to the gate of a triac switching device Q3 which has one power lead 52 thereof
connected to line junction 42 and the remain
ing power lead 54 connected to line junction
48.
In the present practice of the invention, lC2 comprises a device commercially available
from Motoroia Semiconductor Division, Phoe
nix, Arizona, bearing manufacturer's number MOC3041; however, other suitable devices
may be employed.
Referring now to Fig. 1, the power conver
ter 10 of the present invention is shown as
embodied in an installation for a fuel gas
ignition circuit wherein power line terminal H is connected in series with a thermally actu
ated fuel gas valve, indicated generally at 56,
and the power line junction terminal L2 is
connected in series with an electrical resis
tance-type ignitor indicated generally 58.
Referring now to Figs. 1 and 2, the oper
ation of the power converter will be described
wherein the counter IC1 is a octal counter in
which the output of the first register Oc pro
vides a pulse to the base of switch Q. The
counter continues sequencing at line fre
quency until an output exists at register Q4 and resets the counter. In the embodiment
illustrated in Fig. 1, the counter provides a 4to-1 time division for providing power to the
appliance for only one out of four cycles of the line power voltage.
The rectifier diode D1, resistor R1 and capacitor C1 provide a low DC voltage to supply
power to the counter IC1. Resistor R2 functions as a current limiting device and as a voltage divider to enable the line source fre
quency to be applied as a clocking frequency to the clock input terminal 14 of IC1.
Upon receipt of a pulse through R3, Q1 conducts a pulse to LED D2 when the output of register 0o of IC, is high, thereby causing an optical signal to be detected by photocell
Q4. Upon Q4 detecting light emission frorn D2, the emitter of Q4 goes high and provides a
signal to one input of AND Q6. However, Q6 provides no output until a second input signal is received from junction 30. With reference to Fig. 3A, the output of the emitter of G4 is shown as a function of time.
Referring now to Fig. 2, the diode bridge
34 keeps Q5 turned on until the AC line voltage is less than 25 volts or virtually near zero voltage, at which point the positive voltage to the base of Q5 is insufficient to keep the device turned ON. When Q5 switches
OFF, the voltage on junction 30 rises positively thereby creating a HIGH to the second input AND device Q6 If a HIGH exists on both inputs of Q6, the ouput thereof shifts
HIGH giving a pulse through lead 50 to the gate of triac Q3. Upon receipt of a gate pulse, Q3 conducts and provides a signal through output terminal 4.
Referring to Fig. 1, upon triac Q3 providing an output signal through lead 26 to junction 24, a pulse is applied to the gate of power triac Q2 which conducts to provide full load current to the ignitor. Triac Q3 remains ON for 1/2 of the AC line frequency until the next gate pulse occurs. In the arrangement of Figs.
1 and 2, triac (13 is ON for the same time as triac (13 is ON, and thus serves as a relay switching device for applying load current to the appliance. It will be understood, however, that the current rating of power triac (13 is much greater than the power rating of triac 03, internal to IC2. In the present practice of invention the ignitor current is approximately three amperes.
With reference to Fig. 38, the wave form at the base of switching device Q5 is shown wherein at 0.6 volts the collector of Q5 rises to a high positive potential as shown in Fig.
3C. Fig. 3D illustrates the pulse output of
AND device Q6 and Fig. 3E displays the wave form output of triac Q3.
With reference to the foregoing description, it will be seen that the power converter of the present invention provides a convenient way to operate an appliance or load on a power line having substantially greater voltage than the rated operating voltage of the appliance.
The converter of the present invention provides a low cost and simple way of conducting only one out of a specified number of successive power line voltage cycles to the operating load in order to average the higher voltage power to provide the rated power to the load or appliance.
Claims (14)
1. A control device for averaging alternating current electrical power in a load comprising counting means operable to count the successive cycles of an alternating current source, said counting means being operable to reset upon counting a predetermined number of cycles and to emit a signal during only the first of said number of counted cycles, series circuit means connecting said load to an alternating current source, and switch means connected to said series circuit means operative in response to said signal to conduct alternating current power to said load for only one of said counted cycles.
2. A device as claimed in claim 1, wherein said switch means includes a light emitting source and a zero-crossing voltage detector.
3. A device as claimed in claim 1, wherein said switch means includes a triac.
4. A device as claimed in claim 1, wherein said switch means includes a switching device in series with a light emitting source for energizing said light source in response to said signal.
5. A control device for averaging alternating current power in a load comprising series circuit means, including switch means operative to connect and disconnect said load to said alternating current power, and means operative to count successive cycles of said alternating current power and operative to effect closing of said switch means during only one of said counted cycles during a predetermined number of counted cycles.
6. A device as claimed in claim 5, further comprising rectifier means for providing direct current power to said counting means.
7. A device as claimed in claim 5, wherein said counting means emits a signal only when said predetermined number of cycles has been counted.
8. A device as claimed in claim 5, in which said counting means emits a signal only when said predetermined number of cycles has been counted and said switch means includes a light emitting and detecting means operative to emit and detect light upon receipt of said signal for closing said switch means.
9. A control device as claimed in claim 5, wherein said predetermined number comprises four cycles.
1 0. A method of operating an electrical appliance with an alternating current power supply source having a line voltage substan tially greater than the intended operating voltage of the appliance comprising the steps of counting a desired number of successive cycles of passing line voltage, resetting the counter after passage of said predetermined number, providing a control signal during only one of said number of cycles during each counting period, and detecting said control signal and switching line power "on" to said appliance for said one cycle, for providing power thereto for only one of said cycles during said counting period.
11. A method of operating an electrical appliance with an alternating current power source having a line voltage at least twice the intended operating voltage of the appliance comprising the steps of expressing as the nearest fraction whose numerator is one, the ratio of said operating voltage to the line voltage, counting a number of successive alternating current voltage cycles of said line power, said number equal to the square of the denominator of said expressed fraction, and switching said line power to said appliance during only one of said number of counted cycles.
1 2. A method as claimed in claim 11, wherein said step of switching includes switching said line power to said appliance during the first of said number of counted cycles.
1 3. A control device for averaging alternating current electrical power in a load, substantially as hereinbefore described, with reference to, and as shown in, the accompanying drawings.
14. A method of operating an electrical appliance with an alternating current power source having a line voltage substantially greater than the intended operating voltage of the appliance, substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US52185283A | 1983-08-10 | 1983-08-10 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8419506D0 GB8419506D0 (en) | 1984-09-05 |
| GB2144932A true GB2144932A (en) | 1985-03-13 |
Family
ID=24078413
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08419506A Withdrawn GB2144932A (en) | 1983-08-10 | 1984-07-31 | Programmable AC power line converter |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2144932A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2166009A (en) * | 1984-08-17 | 1986-04-23 | Hayashibara Ken | Frequency divider circuit |
| EP0311031A2 (en) * | 1987-10-06 | 1989-04-12 | Grundfos International A/S | A method and an electric circuit for controlling an AC-motor, and a circulation pump driven by a motor controlled in this manner |
| GB2221360A (en) * | 1988-07-26 | 1990-01-31 | Ma Gil Pyung | Constant power control of electric heater for alternative supply voltages |
| GB2232468B (en) * | 1987-06-23 | 1992-01-08 | Robertshaw Controls Co | Improvements in or relating to control means for a heating element means |
| WO1995010875A1 (en) * | 1993-10-12 | 1995-04-20 | Fischer, Helmut | Power supply for standby circuits of electrical devices |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2041674A (en) * | 1979-02-01 | 1980-09-10 | Gen Electric | Power control for resistive heater using high inrush current element |
| GB2041673A (en) * | 1979-02-01 | 1980-09-10 | Gen Electric | Power control for resistive heaters |
-
1984
- 1984-07-31 GB GB08419506A patent/GB2144932A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2041674A (en) * | 1979-02-01 | 1980-09-10 | Gen Electric | Power control for resistive heater using high inrush current element |
| GB2041673A (en) * | 1979-02-01 | 1980-09-10 | Gen Electric | Power control for resistive heaters |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2166009A (en) * | 1984-08-17 | 1986-04-23 | Hayashibara Ken | Frequency divider circuit |
| GB2232468B (en) * | 1987-06-23 | 1992-01-08 | Robertshaw Controls Co | Improvements in or relating to control means for a heating element means |
| EP0311031A2 (en) * | 1987-10-06 | 1989-04-12 | Grundfos International A/S | A method and an electric circuit for controlling an AC-motor, and a circulation pump driven by a motor controlled in this manner |
| EP0311031A3 (en) * | 1987-10-06 | 1990-12-27 | Grundfos International A/S | A method and an electric circuit for controlling an ac-motor, and a circulation pump driven by a motor controlled in this manner |
| GB2221360A (en) * | 1988-07-26 | 1990-01-31 | Ma Gil Pyung | Constant power control of electric heater for alternative supply voltages |
| FR2634964A1 (en) * | 1988-07-26 | 1990-02-02 | Gil Pyung Ma | Constant-power supply unit for electrical heating apparatus |
| NL8901614A (en) * | 1988-07-26 | 1990-02-16 | Gil Pyung Ma | POWER SUPPLY FOR AN ELECTRIC HEATING APPLIANCE. |
| GB2221360B (en) * | 1988-07-26 | 1993-01-27 | Ma Gil Pyung | Constant power supply unit of electric heating apparatus |
| WO1995010875A1 (en) * | 1993-10-12 | 1995-04-20 | Fischer, Helmut | Power supply for standby circuits of electrical devices |
| US5642004A (en) * | 1993-10-12 | 1997-06-24 | Helmut Fischer | Power supply for standby circuits of electrical devices |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8419506D0 (en) | 1984-09-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |