AU4053593A - Controller for irrigation apparatus - Google Patents

Description

CONTROLLER FOR IRRIGATION APPARATUS FIELD OF INVENTION

The present invention relates to the field of apparatus used for control of fluid flow. Fluid (gaseous or liquid) control apparatus often provide certain control functions by way of remote electrical devices, such as solenoids. In one form, the control apparatus of the present invention has application in the field of irrigation, where actuation of solenoid valves can be used to control water flow. BACKGROUND ART

An Electronic Irrigation Controller requires power, an accurate clock and timers to "switch on" and "switch off" its associated solenoids. The vast majority of irrigation controllers on the market today require a 110 - 220/240 volt AC power source. Such a power source is often not available at the point where irrigation is required or the cost of providing this power is often prohibitive.

Electronic Irrigation Controllers utilizing solar power are becoming more frequently used, however, problems exist. Excessive drain of power reserves over prolonged periods of relatively overcast weather conditions cause problems. This is often due to the relatively large amount of power which is consumed by prior art irrigation control apparatus, whether or not control valves are actuated and is due to the power requirements of various power and clocking circuits internal of the controller.

Australian patent application No. 48316/90 relates to an irrigation controller marketed under the brand "LEIT 8000", a trade mark of Solatrol Inc., USA.

The disclosure of patent application No. 48316/90 specifies that problems exist in utilizing solar arrays in powering irrigation control systems. It is noted that in order to satisfy the leakage and power consumed by a irrigation control system, a solar array of many square feet, typically at least 6 square feet, would be required to collect adequate solar energy. A solar array this large is relatively expensive, challenging to install and usually unsuitable for commercial and residential irrigation applications. The patent application contemplates the use of high performance or "super" capacitors capable of storing large amounts of energy. The patent application also contemplates the use of power sources other than only solar power sources. The patent application also contemplates the use of DC latching solenoids. This enables the apparatus contemplated by application No. 48316/90 to become fully "awake" and to operate control irrigation stations for only very short periods of time, of the order of fractions of a second, with typically long time separations, of the order of minutes or hours. The controller disclosed typically "awakes" for 10 milliseconds of every second. Problems will be encountered, however, where the DC latch remains "on" due to a fault.

It has been found that the "LEIT 8000" is a self monitoring device. It monitors its own internal electronics to economize on power. It has been found that the device cannot monitor or power any external DC or AC operated commercial electronic watering system clock and that the device is completely "dead" or inoperative when not awake. This may lead to relatively slow response times, or even failure to acknowledge that irrigation is required. It has also been found that it can only operate DC latching solenoids associated with its on board 8 station watering clock. OBJECTS OF THE INVENTION

An object of the present invention is to provide a controller apparatus for remote control of electrical devices. A further object of the present invention is to provide a control apparatus which has reduced demands on power supply. SUMMARY OF INVENTION

The present invention provides a control apparatus adapted to actuate a remote device, said controller being adapted to receive or provide timing signals which are indicative of periods of time in which the remote device is to be actuated, said apparatus comprising: an inverter for providing an actuation signal to the remote device, and logic means adapted to switch the inverter between active and idle states in response to the timing signals. The present invention provides a control apparatus adapted to provide power to a remote device, said apparatus comprising: timing input means adapted to receive a timing period signal from an external timing source, the timing signal serving to indicate that power is to be provided to the remote device, inverter means adapted to switch to an "on" state and provide said power in response to the timing signal, wherein, upon removal of the timing signal the inverter reverts to an "off" state.

The present invention is predicated on the discovery that a controller apparatus may be provided to power to a remote device by utilizing an onboard inverter. The present controller serves to attain significant economy in power consumption over a period of time by switching the inverter between an "on" or active state and an "off" or idle state. In an active state, the inverter provides power as required, whether the power is 12, 24, 110, 240 or whatever voltage. Power can be provided either DC or AC, as is required by the remote device, for example an irrigation solenoid.

In an "idle state", the inverter is not operational. The controller samples intermittently for a timing interval from an external clock, after receipt of which the inverter can again be switched to an active state.

A fluid control apparatus which is cycled or alternated between "active" and "idle" states, can consume substantially less power than prior art controllers and therefore less dependent on power supply reserves, such as batteries.

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

Figure 1 shows in schematic form an automated irrigation system. Figure 2 shows in schematic form the controller, incorporating the inverter, of the present invention in association with a customer supplied irrigation clock.

Figures 3, 4 and 5 show, in circuit diagram form, another embodiment of the present invention, being a microprocessor version of the invention. Figure 3 shows the microprocessor drive, figure 4 the inverter and coupling to an external clock and figure 5 the controller electronics. Although the present invention is disclosed with regard to an irrigation controller, the scope of the invention should not be limited to such application. For example, the inverter and controller of the present invention has general application both commercial and domestic wherever voltage conversion or supply is required. Voltage conversion may be provided from 12vDC to 240 or 110AC; the 12v supply may be provided from solar cells.

The present controller can also be used in security systems, for sampling and controlling sensors and alarms, or for garden lighting.

Unlike, prior art devices, the present invention however is not a self contained electronic watering clock, its function is to monitor and power any commercial AC actuated electronic clock and its associated electrical devices. The device of the present invention in a preferred form draws its power from a 12v DC battery which is charged by solar cells. This 12v DC power is inverted to provide a low 24v AC voltage or other voltage as required. The present apparatus eliminates the need to reticulate domestic power from the local grid as it supplies power and operates the irrigation controller using readily available solar energy.

The present apparatus when used as an irrigation controller regularly or randomly looks for any or all of the preset watering times which have been set into the memory of any commercial multi-station electronic Irrigation Controller. The present apparatus can be fitted as an adjunct to existing control apparatus.

The "Timed Sampling" unit of the present invention, is an electronic module that regularly looks for any or all of the present watering times that have been set into the memory of any external or connected commercial multi station electronic water controller. The present unit is able to be electrically coupled to a timing output port of any commercial station. The present unit is activated upon detection of a watering signal from the preset unit to enable watering.

The present unit remains activated while the watering signal is present.

The present unit is deactivated by cessation of the watering signal. Preferably the unit strobically samples for detection of a watering signal. The interval between samples may be varied according to the regularity of watering required by a particular environment. The sampling may also be done on a continuous or random basis, as required.

When the present unit "finds" the start time of one or more watering periods ,it "latches on" and completes the watering period, then it drops back to its sampling or idle state until it finds the next preset period.

Only during the "latched on" or active state period is the Timed Sampling units' inverter running to power the electronic clock and its solenoids. At all times a crystal clock in the Timed Sampling unit keeps accurate time.

The Timed Sampling unit, in one form, consists of: (a) Variable Time Sampler

(b) 12 Volts DC to 24 Volts AC Inverter

(c) Crystal controlled clock

(d) 16 watt - 12 volt Solar- array panel

(e) 12 volt - sealed 17.2 amp. hr Battery. The present invention provides a substitute low power or high power AC voltage source replacing the 240v AC power source often used in reticulated electric supply.

In one preferred form, the 12 volt DC battery used as the power source is kept charged by a solar cell which is regulated to remove the possibility off damaging the battery or the circuitry by overcharging. The electronic circuitry fits inside the body of the host controller so that a minimum number of connections need be made when the system is installed.

Major features of the controller include:

Solar-Batterv o^peration. The irrigation controller is operated from a 12vDC battery which is charged from a solar cell. Even on relatively dull days there is sufficient solar energy captured to allow normal operation on most systems. With unusually large systems where long watering times may be required, it is simple for the controller to handle by increasing the size of the battery and solar cell or increasing the number of batteries and solar cells. Safe Operating Voltage. The use of the extra low voltage 12vDC ensures safety because there is no requirement for dangerous 240vAC power supply. This also means that the system does nol have to be installed by a Licensed Electrician. Furthermore the use of regular solenoids rather than latching solenoids required by prior art battery powered controllers means that there is no dangerous DC in the ground. Direct Current in the ground is a significant attraction for lightning.

Low Maintenance. The use of maintenance free sealed batteries and solar cells ensures maintenance free operation. In addition the use of solid state electronics and an absolute minimum of external connections ensures reliable operation. Once the system is installed it requires no maintenance except as recommended by the controller manufacturer.

The only external connections are those between the solar cell, the battery, the controller, and those to the watering solenoids.

Maximizes Battery Life. The battery life of the system is maximized by reducing the power consumption of the controller. This is achieved by running only the clock memory until the watering cycle commences and then supplying full power to the solenoid control circuits during the watering cycle regardless of whether this occurs during the day or night.

By this method the battery charge is maintained at the highest possible level thus reducing battery cycling.

Accurate Time Keeping. The controller includes a crystal locked time base which provides a stable signal to ensure accurate timekeeping by the clock.

The controller in an irrigation application has many benefits over a prior art electronic irrigation controller, including:

Solar-Battery operation which provide a 'no-break' mode of operation for the irrigation system. • Replaces 110-220/240 VAC power supply with safe extra low voltage supply. Accurate crystal locked time base to keep continuous correct time • the controller does not compromise or deteriorate any of the features and facilities provided by the host electronic irrigation controller. Rather it enhances these features and facilities by ensuring their continuous operation. • the controller maximises battery life by running only the clock memory until the watering cycle commences. the controller is designed for night-time operation. However it can easily be used in daylight hours by simply depressing the night-time override switch, using the controller saves on costly installation of 110-220/240VAC power supply.

• the controller uses low maintenance batteries and solar cells.

With regard to figure 2, the operation of the controller will be explained. The controller operation is exemplified with the controller operatively coupled to an external irrigation clock. anual O eration

A momentary contact manual over-ride switch is connected in parallel with relay R2. When the external clock is set in the manual watering position the manual over-ride switch will causes relay R1 to operate. R1 turns the inverter on. The output of the inverter is supplied to the AC input of the external clock. This in turn causes an output voltage at the pump terminals of the external clock causing R2 to operate and hold the inverter power "on" while the external clock is in the watering state. Automatic Irrigation

In one preferred form, R1 is set for operation at 7 minutes off, 14 second on which functions in a strobic manner. The timing between active and idle states may alternatively be random, i.e. varied in duration. During the 14 second on time of the sampling unit relay R1 operates. R1 turns the inverter on. The output of the inverter is supplied to the AC input of the external clock. If the external clock has been programmed to turn on at this time, (set by garden staff) there will be an output voltage at the pump terminals of the external clock, causing R2 to operate and hold the inverter power on whilst the external clock is in the watering state. If the external clock had not been set to turn on at this time, then when the 14 seconds has elapsed the inverter will power down and the sampling unit will return to its 7 minutes off, 14 seconds on mode, until the next strobic cycle or until a predetermined time has been set in the external clocks program. This 5 feature provides significant improvement in attaining a low power consumption relative to prior art controllers. Operation of Controller

The controller has two modes:

1 ) Night time operation (Sampling runs only at night)

10 In daylight clock time and programmed functions kept by 50Hz time base in inverter

2) 24 hour operation (Sampling runs all the time)

In the night time mode the external clock can only be used between nightfall and dawn (an over-ride switch can be used to manually water in 15 daylight).

The controller comprises of a dual timer. This timer functions to provide the 7 minutes off, 14 seconds on strobic timing. The timer may be preset or varied according to the particular application to which the present invention is put. 20 Basic Operation of Controller's Inverter

The inverter essentially has two transistors which are switched on and off alternatively. That is one is off, the other is on, and vice versa. Operation of Inverters Transformer

When one transistor turns on, 12v is applied to half of the transformer 25 primary, a further 12v is induced in the other half of the winding (by transformer action). The circuit is configured such that the collector of the other transistor has 24v applied to it, similarly when the other transistor turns on and one is off, one has 24v applied to its collector. The resulting 50Hz square wave applied to the transformer induces a nominal 24 volts at the transformer. The output is a 30 24vAC, tapped at 12v and 15v. Diodes protect the output transistors from the back EMF generated by the transformer winding. The inverter is put into idle mode by use of a Tri-state buffer, used in association with the inverter transistors.

The power for the inverter is derived from a 12v battery via R1 and the resultant 12v switches on the tristate buffer, which is normally off in the inverters idle mode. When watering is required as determined by the signal from the pump outlet of the external clock, the inverters output is connected to the 24 volt AC input of the external clock. While the clock is in the watering mode the inverter will be held in the sampled state by relay R2 which derives its power from the pump output of the external clock. Protection

The use of state of the art components in the inverter, such as the Tri-state strobed hex inverter/buffer insures a high degree of reliability of the inverter in the switch on mode, as well as it's switch off mode.

It is the provision of the tristate IC which provides a positive On and Off. This protects the inverter against false starts.

The preferred component is a 4502IC Tri-Start strobed hex inverter/buffer which no other inverter has built into it.

It can be used in any domestic application as it can be turned into a 240 volt component - but, in the disclosed application it's use is for low voltage power.

Basic Operation of Inverter

Two anti-phase signals from the fixed frequency time base (50Hz) are used to drive a transistor output stage. Other frequencies may be used where the controller is used, for example 60 Hz in USA. These transistors are in turn used to drive a transformer which steps up the output voltage to 12v, 15v, 25v

AC.

A fixed oscillator is used to divide down the crystal frequency to 50Hz. The 50Hz output is divided into two outputs, one directly into the external clock AC input. Pulse is calculated so as to run the external clock on the minimum amount of current to minimise the drain on the battery in its idle time (external clock watering cycle not in use). The other output of 50Hz oscillator is fed into a phase locked loop (PLL) which has been used to give a 50% duty cycle wave form. The output from the PLL is a genuine square wave and when it is locked in, the output frequency is equal to the input frequency of the oscillator. The output from PLL is buffered by inverter the Tri-state strobe hex inverter/buffer to provide drive to one inverter transistor. Another part of the tri¬ state buffer is used to provide a 180 degree out of phase complementary drive signal for the other inverter transistor.

The inverter transistors, one for each phase, are connected across the transformer primary. Base drive current is limited and this ensures low saturation voltage at maximum load. Microprocessor version

The sampling function of 7 minutes off and 14 seconds on can be supplied by a microprocessor or other device which supplies an on/off signal with a significantly high "off time. The sampling rate can/may be varied from the above to give timing in fractions of a second to many hours if required. This would not detract from the scope of the invention.

Further more it may be found to be convenient to use continual sampling where the "off time is zero, provided that the 50Hz memory backup is kept in its idle state until watering is required:

In the controller, switching functions are achieved by relays and there associated contacts, but in the microprocessor version, all of the functions will occur in the micro processors soft ware program. This use of relays will still be an option depending on the application of the controller in the irrigation industry or other commercial application.

Reference is made to figures 2, 4 and 5 in relation to a description of the microprocessor version.

The microprocessor controller control apparatus uses continual sampling where the off time is zero. However, the off time may be variable or preset at a predetermined time, depending upon the application of the control apparatus. A

50Hz memory backup is kept in its low power idle state until watering is required. When the controller detects a signal from the pump output of the electronic irrigation controller, the microprocessor is interrupted and the inverter is switched from low power mode to high power mode until watering sequences have been completed. The microprocessor then goes back to low power idle mode. FEATURES OF THE MICROPROCESSOR VERSION

1 ) This device converts a nominal 12 volts DC battery supply to a 50/60Hz AC supply 12v, 15v, 24v suitable for powering a variety of commercial brand electronic irrigation controllers.

2) Very low quiescent current for extended battery life. 3) Intelligent load sensing ensures maximum battery capacity.

4) Crystal locked microprocessor circuitry for accurate and precise control.

5) Automatic shutdown on output overloads exceeding 1 minute.

6) Automatic shutdown on low battery voltage with automatic restart or normal voltage. INVERTER DRIVE

The controller's Microprocessor electronic module consists of two drives

1 ) Low Power Drive from micro LP01 , LP02 outputs A2, B1 , T1 and T4.

2) High Power Drive from micro HP01 , HP02 outputs A1 , B2, T2 and T3. A1, A2, B1 , B2 are buffer drivers (LM327N) for the bases of Darlington Transistors T1 , T2, T3, T4 (BD649).

T1 and T4 are the low power drive to Tran 1 (Inverter Transformer). T2 and T3 are the high power drive to Tran 1.

All inverting inputs are common to bias level formed by R1 , R2 and Diode D1. A preferred mode bias is 2.5 volts. Microprocessor outputs drive all non inverting amplifier inputs, A1 , A2, B1 ,

B2 (LM327N). SEQUENCE OF LOW POWER OPERATION

Microprocessor outputs go high when the A2 operational amplifiers output (LM327N) are high, turns on Darlington Transistor T1, pulls collector low, applies 12v to half of Tran 1 , a further 12v is induced in the other half of Tran 1

(by transformer action), so that the collector T4 has 24v applied to it, similarly when B1 and T4 turns on T1 is off. T1 has 24 volt applied to its connector. The resulting 50Hz square wave applied to the transformer induces a nominal 24 volts AC at the transformer secondary winding. SEQUENCE OF HIGH POWER OPERATION

Similarly as in above but using high power output of microprocessor A1 , T2, B2 and T3.

Diodes D7 and D8 protect the output transistor T2 and T3 in high power mode from back EMF generated by transformer winding.

R16, R17, R18 and R19 are resistors protecting the microprocessor from the operational amplifiers A1, A2, B1 and B2 bias current. OVER CURRENT SHUTDOWN PROTECTION

Operational amplifiers A3 and A4 are wired as a latching circuit with a trip level, the voltage on Diode (0.6 volts at A3 and input).

All emitters of drive transistors T1 , T2, T3, and T4 are common to resistor RC. If the drive current exceeds 6 amps, then 0.6 volts appears across RC and latching circuit trips as follows. A3 output goes low A4 non inverting input pulled low A4 inverting input is held high by microprocessor A4 output goes high D 2 conducts

A3 inverting input held high

D3 also conducts and forces the bias on inverting inputs inputs A1 , A2, B1 and B2 high (approximately 10 volts) Therefore all outputs of A1 , A2, B1 and B2 go low and remove bias to driver transistors irrespective of microprocessors state.

Microprocessor is signalled by latched (overload) state, via R4 and diode D4. D4 protects the microprocessor at 5 volts.

Microprocessor waits 2 seconds then applies a 50 microsecond reset pulse to the non inverting input of A4 negative pulse. Non inverting input low, then output low, therefore Diode D2 is now conductive and if resistor RC has less than 6 amps flowing in it, then latch circuit A4, A3 returns to normal (reset). Drive from microprocessors is re-enabled as Diode D3 is not conducting, if short circuit or overload has cleared then circuit resumes normal operation, if present. Then A4 and A3 instantly relatch. POWER SUPPLY Regulator Reg1 reduces 12/14 volt DC battery supply into +5 volts regulated for microprocessor and also +5 volts is fed as a reference bias B3 operational amplifier.

A voltage divider from +12 volts, R5, R6 provide a bias to non inverting input of operational amplifier B3 at approximately 6 volts when positive feedback applied via R7. If 12 volt supply drops, the non inverter bias drops, and when it reaches less than 5 volts, B3 operational amplifier output goes low and signals the microprocessor of a low voltage condition via R8 and Diode D5. PUMP OUTPUT

When the pump output from electronic irrigation controller is energised, a signal is applied to opto coupler OC1 to interrupt the microprocessor, and then changes state from low power to high power.

The RC network R10, R11, R25 and capacitor is designed to filter out the high voltage spikes coming from pump output when de-energised. MICROPROCESSOR OPERATION 1. On power up the microprocessor applies alternating assertion pulses to the HP01 and HP02 points to generate high power inversion to initialise the commercial electronic irrigation controller for two seconds.

Also, the overload latch is reset to ensure it initialises in the correct state. 2. After the two seconds, the micro switches to alternating assertion pulses to LP01 and LP02 to provide power saving low power to electronic the external irrigation controller via A2, B1 and T1 and T4. It will stay in this mode, unless: a) micro overload input to microprocessor goes to +5 volts. It then tries 32 times to reset overload latch (Micro Reset) every 2 seconds (2 minutes maximum). If successful go to step (2) or else leave overload and wait for manual/auto switch to be cycled (or power re-applied) and then go to (1), b) device is switched from auto to manual, this stops pulses LP01 , LP02 and starts pulses to HP01 , HP02 to supply full power on manual demand to electronic irrigation controller and stays in high power mode until switch goes to auto, or c) pump input from electronic irrigation controller causes interrupt (IRQ) to microprocessor, go to (2)B. 3. The assertion enabling pulses are derived from a crystal oscillator on board the microcontroller such that the crystal frequency chosen divides to exactly 10m/sec (50Hz) to provide accurate timing to the electronic irrigation controller.

The controller of the present invention is adapted to interface with many external clock apparatus. In the field of irrigation, the embodiments described can interface with electronic controllers such as: a. All Richdel™ electronic water controllers b. All Oasis™ electronic water controllers c. Or any other brands with AC input and pump output. d. TORO™ range of electronic clocks.

Vision™ I and π series e. TORO™ system "C" controller. THE ORDER OF WIRE CONNECTION TO ELECTRONIC WATER CONTROLLERS 1. Connect transformer wires to electronic water controllers (blue, black, green and purple as instructed on previous page).

2. Connect pump wires to electronic water controller (pump and common) grey wires.

3. Connect solar cell to electronic modules solar input, red wire to positive connection and black wire to negative connection.

4. Connect the 12 volt battery to the electronic modules battery input, red wire to positive connection and black wire to negative connection.

On connection of the battery and solar cell the display on the electronic water controller will display a time or will be flashing. The electronic water controller will now be able to programmed as per its manufacturers instructions. If there is no display disconnect battery and solar cell and check wiring. The controller via the transformer in one form is configured as a load sensing device. When the device senses a load, the microprocessor switches from low to high power mode. FURTHER EMBODIMENT The embodiment disclosed above operate on a voltage sensing principle, whee the controller senses voltage from an external clock and in response to a change in voltage, the present controller turns itself from an idle state to an active state.

With reference to figure 5, a further current sensing embodiment may be implemented with relatively small modification. The modification seeks to sense voltage across the RC resistor, and by using a comparator circuit, at a preset or predetermined voltage it is possible to trigger the interrupt input of the microprocessor directly. Thus the opto-switch, delay and bridge circuits of the present figure 5 are not required.

Claims (6)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A control apparatus adapted to provide power to a remote device, said apparatus comprising: timing input means adapted to receive a timing period signal from an external timing source, the timing signal serving to indicate that power is to be provided to the remote device, inverter means adapted to switch to an "on" state and provide said power in response to the timing signal, wherein, upon removal of the timing signal, the inverter reverts to an "off" state.

2. An apparatus as claimed in claim in claim 1, wherein the timing means is adapted to sample for the timing signal intermittently.

3. A control apparatus adapted to actuate a remote device, said controller being adapted to operatively couple to a source of timing signals, the timing signals being indicative of time periods in which the remote device is to be actuated, said apparatus comprising: an inverter for providing an actuation signal, and logic means adapted to switch the inverter between on and off states in response to the timing signals.

4. A control apparatus adapted to interface with an external clock means, comprising: logic means adapted to strobically interrogate or monitor the external clock means, the logic means being adapted to alternately function between an active state, for interrogation purposes, and an idle state, to enable reduced power consumption by the control apparatus.

5. A control apparatus as claimed in claim 4, where the interrogation of the external clock means is randomly timed.

6. A control appartus as claimed in claim 4 or 5, wherein in the active state, an inverter means for providing power to an external device is enabled.