Ballast circuit and method for optimizing the operation of high intensity discharge lamps in the growing of plants
First Claim
1. In a chamber for growing plants having at least one high intensity discharge lamp, means for supplying current pulses having an alternating polarity to said lamp for providing light beneficial to the growth of said plants, first means including a sensor providing a signal having a value representative of the current flowing through said lamp, second means including a sensor providing a signal representative of the value of voltage across said lamp, a microprocessor responsive to said first and second means for correlating the values of both said current and voltage to regulate the power to said lamp and thereby control the lamp'"'"'s operation by controlling the amount of power supplied to said lamp by said pulse supplying means, and third means having a sensor providing a signal having a value representative of the temperature of said means for supplying current pulses, the value of said temperature signal being correlated by said microprocessor with the values of said current and voltage signals to thereby additionally control said lamp in accordance with the temperature of said means for supplying current pulses.
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Abstract
At least one high intensity discharge lamp is utilized in the growing of plants within a growth chamber. The lamp is connected to a power supply that provides pulses of alternating polarity to the lamp through a ballast which first provides a relatively high inductance and which after lamp current has reached a certain level provides a matched T-configured impedance network. Initially, a microprocessor, there being one for each lamp ballast (or one for a group of lamps), closes a switch to connect the lamp to the power supply through a step-up transformer, the secondary winding of which during start-up contributes to the high impedance condition during the early stage of lamp operation and which is thereafter part of the T-network. When the lamp is ionized, both the lamp current and the lamp voltage are sensed. The ballast microprocessor uses the signal derived from the current sensor for the lamp with which it is associated to open the switch and thus remove the high voltage from the particular lamp it controls. Thereafter, the microprocessor, in each instance, causes the frequency of the power supply to be adjusted in discrete steps and to also adjust the inductance of the T-network to effect an optimization of the lamp load. Various temperature and light signals associated with the growing of plants can also be sensed and the microprocessor programmed to correlate these additional signals with the current and voltage signals in providing its optimized control of each lamp within the growing chamber. A supervisory processor or facility computer exercises control over whatever number of individual ballast microprocessors and lamps have been selected for the cultivation of plants within the growth chamber.
91 Citations
47 Claims
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1. In a chamber for growing plants having at least one high intensity discharge lamp, means for supplying current pulses having an alternating polarity to said lamp for providing light beneficial to the growth of said plants, first means including a sensor providing a signal having a value representative of the current flowing through said lamp, second means including a sensor providing a signal representative of the value of voltage across said lamp, a microprocessor responsive to said first and second means for correlating the values of both said current and voltage to regulate the power to said lamp and thereby control the lamp'"'"'s operation by controlling the amount of power supplied to said lamp by said pulse supplying means, and third means having a sensor providing a signal having a value representative of the temperature of said means for supplying current pulses, the value of said temperature signal being correlated by said microprocessor with the values of said current and voltage signals to thereby additionally control said lamp in accordance with the temperature of said means for supplying current pulses.
- 2. In a circuit having at least one high intensity discharge lamp, power means for supplying electrical pulses having an alternating polarity to said lamp, means for controlling said power means to provide a relatively high frequency or repetition rate of said pulses when starting said lamp, and means responsive to current flowing through said lamp for causing said controlling means to abruptly reduce said frequency after said lamp has been started.
- 11. In a chamber for growing plants, a plurality of high intensity lamps, a microprocessor associated with each lamp and responsive to both lamp current and lamp voltage for controlling the power to each lamp, respective means for supplying current pulses having an alternating polarity to each lamp, each of said microprocessors determining the frequency of said pulses, and a computer for exercising supervisory control over each microprocessor.
- 13. A circuit comprising a plurality of high intensity lamps, means for supplying current pulses having an alternating polarity to each lamp, said current pulses determining the lamp load in each instance, a microprocessor for controlling the load of each lamp, each of said microprocessors determining the frequency of the pulses supplied to the lamp with which it is associated and changing the frequency of said pulses in a step-wise manner, a saturable core reactor for each lamp, each saturable core reactor having a power winding in circuit with the lamp with which it is associated and a control winding energized via the particular microprocessor for controlling the load of the lamp with which it is associated, and a computer for exercising supervisory control over each microprocessor to cause said respective loads to be simultaneously increased or decreased.
- 18. A circuit for controlling the operation of a high intensity discharge lamp comprising a high intensity discharge lamp, power means for supplying current pulses having an alternating polarity, inductance means connected between said power means and said lamp, means for sensing the flow of current through said lamp, and means responsive to a signal derived from said current sensing means for step-wise changing the frequency of said alternating current pulses supplied by said power means to avoid resonance and to cause said power means to supply a constant amount of power to said lamp.
- 25. A lamp ballast circuit comprising a high intensity discharge lamp, power means for supplying electrical pulses of alternating polarity to said lamp, variable inductance means between said power means and said lamp through which said electrical pulses flow, means for increasing the inductance of said inductance means when starting said lamp, means for also increasing the frequency of said pulses when starting said lamp, and means for reducing the frequency of said pulses after said lamp has started.
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27. A lamp ballast circuit comprising a high intensity discharge lamp, power means for supplying electrical pulses of alternating polarity to said lamp, variable inductance means between said power means and said lamp through which said electrical pulses flow, means for increasing the inductance of said inductance means when starting said lamp, means for also increasing the frequency of said pulses when starting said lamp, and means responsive to current flow through said lamp for reducing the frequency of said pulses after said lamp has started, said frequency reducing means including a microprocessor.
- 31. A lamp ballast circuit comprising a high intensity discharge lamp, power means for supplying current pulses of alternating polarity, a T-network including first, second and third impedance legs, said first leg having a first inductance coil, said second leg having a second inductance coil in parallel with the third inductance coil, said third leg having a capacitor with one side of said capacitor being connected to the junction of said coils, a first control winding inductively associated with said second coil, a second control winding inductively associated with said third coil, a microprocessor for energizing said first control winding to provide a high voltage to said lamp to effect ionization thereof, and means responsive to current flow through said lamp after ionization for causing said microprocessor to de-energize said first control winding and to energize said second control winding to control the flow of current through said lamp.
- 34. A lamp ballast circuit comprising a high intensity discharge lamp, power means for supplying electric pulses of alternating polarity, inductance means between said power means and lamp, a first winding associated with said inductance means for applying a high voltage spike to said lamp to start said lamp, current sensing means, means controlled by said current sensing means for de-energizing said first winding, means for initially causing said power means to supply electric pulses to said lamp at a relatively high frequency, means responsive to lamp current for causing said power means to supply electric pulses to said lamp at a relatively low frequency, a second winding associated with said inductance means for controlling the inductance of said inductance means to regulate the width of said electric pulses by controlling the inductance of said inductance means.
- 38. A method of controlling the operation of a high intensity discharge lamp comprising the steps of initially supplying current pulses of alternating polarity to a lamp at one frequency, adjusting the amount of inductance to control the supply of current pulses to said lamp, deriving a signal representative of the current flowing through the lamp at any given moment and utilizing said signal in continuously controlling the frequency in a step-wise manner to assure that acoustical resonance is at all times avoided.
- 42. A method of controlling the operation of a high intensity discharge lamp or the like in which current pulses of alternating polarity are supplied through a matching impedance network, a pair of inductances in series with said lamp through which said pulses are supplied and a capacitor in parallel with said lamp, said capacitor being connected to the juncture of said inductances, the method comprising the steps of adjusting the frequency at which said pulses are supplied so as to achieve a predetermined control of said impedance network, varying the magnitude of one of said inductances, deriving a signal representative of the current through said lamp after ionization thereof, in using said signal to adjust the frequency at which said pulses are supplied to avoid electrical resonance in said network and to avoid acoustical resonance in said lamp.
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47. In a chamber for growing plants having at least one high intensity discharge lamp, means for supplying current pulses having an alternating polarity to said lamp for providing light beneficial to the growth of said plants, first means including a sensor providing a signal having a value representative of the current flowing through said lamp, second means including a sensor providing a signal representative of the value of voltage across said lamp, a microprocessor responsive to said first and second means for correlating the values of both said current and voltage to regulate the power to said lamp and thereby control the lamp'"'"'s operation by controlling the amount of power supplied to said lamp by said pulse supplying means, and third means having a sensor providing a signal representative of the temperature of said lamp the value of said temperature signal being correlated by said microprocessor with the values of said current and voltage signals to thereby additionally control said lamp in accordance with the temperature of said lamp.
Specification