Patent Application
20080232977
The present invention relates to a pump, and more particularly to a control system for the pump.
A submersible pump is typically activated to pump water from a well into a connected water tank such that the water pressure within the tank remains within predetermined levels. However, the submersible pump can overheat in a relatively short amount of time if water is unavailable to be pumped to the tank. Additionally, since the number of pump-on times is directly proportional to pump wear, more pump-on time will wear out the pump at a faster rate.
Accordingly, there is a need for a pump control system that detects water availability. In one form, the invention provides a pump control system that includes a water pump, a pressure transducer, a current phase detector, a voltage phase detector, and a micro-controller (“MCU”). When an AC signal is supplied to the pump, the current transducer and related circuitry will sample the AC signal and send the sampled AC signal to a current phase detector whose output indicates an operating current phase of the pump. The output signal of the current phase detector is then fed into the MCU. Meanwhile, an operating voltage of the pump is fed into a voltage phase detector whose output indicates an operating voltage phase of the pump. The output signal of the voltage phase detector is similarly fed into the MCU.
The system also includes a current transformer from which the pump operating current is sampled. The extracted pump operating current is sent to an amplifier to yield a squared current signal. Similarly, the voltage signal is also fed to a second amplifier to yield a squared voltage signal. Both the squared current signal and the squared voltage signal are subsequently sent to the MCU for processing. The MCU determines an actual phase angle difference between the squared current signal and the squared voltage signal. Since the determination process is performed digitally, variations in the operating voltage signals and current signals have minimum or no effect on the process. In this way, inaccuracy and inconsistency of phase angle detection caused by inaccuracy and inconsistency of transistors and amplifiers of the circuits can be minimized or avoided. Furthermore, discretely processing the phase angle allows the system to adjust or control the phase angle settings when different pumps are used for the system.
Additionally, modified amplitudes of the current and voltage signals are filtered and fed into a comparator circuit. The comparator circuit then compares the filtered signals with some reference values. The comparator outputs are subsequently fed into the MCU. The MCU thus outputs a signal to activate a plurality of solid state relays. A display such as an LED, can also be coupled with the MCU to indicate the water pressure detected by one or more semiconductor pressure transducers.
In one construction, the invention provides a pump control system for controlling a fluid pump powered by an AC signal. The pump control system includes a signal phase detector coupled to the fluid pump to detect the AC signal supplied to the fluid pump and to generate phase signals indicating a phase parameter of the AC signal. The pump control system also includes a micro-controller to receive the phase signal and to generate a rectified output signal based on the phase signals, and a relay to control the power supplied to the fluid pump based on the output signal of the micro-controller.
In another construction, the invention provides a pump control system for controlling a fluid pump powered by an AC signal. The pump control system includes a signal phase detector to detect the AC signal supplied to the fluid pump. The AC signal typically has an AC current component and an AC voltage component. As a result, the signal phase detector then generates a phase signal indicating a phase shift between the AC current component and AC voltage component. The pump control system also includes a micro-controller to receive the phase signal and to generate a rectified square wave signal based on the phase shifts, the AC current component and AC voltage component, and a relay to disconnect and to connect the power supplied to the fluid pump based on the rectified square wave signal of the micro-controller.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings.
The second subsystem includes a pressure signal amplifying circuit 144. The pressure signal amplifying circuit 144 includes a plurality of operational amplifiers 140, 146, and 148, and potentiometers 136, 150, 152, and 154. Among the potentiometers, potentiometers 136, 150, and 152 are used to adjust or tune a zero-pressure balance of the amplifying module 104, while the other potentiometer 154 is generally used for gain adjustment. In this way, the operator of the system 100 can adjust the potentiometer 154 to calibrate the pressure reading when a reference pressure is applied to the pressure fitting. As a result, no adjustment is necessary for manufacturing or producing these parts in general. This allows the operator to use other similar pressure transducer while maintaining linearity of the pressure transducer.
The pressure range selection circuit 112 includes a hydraulic pressure adjustment circuit 156. By fine tuning the hydraulic pressure adjustment circuit 156, the pump control system 100 can regulate a maximum amount of hydraulic pressure the MCU 108 can measure. The hydraulic pressure adjustment circuit 156 includes a voltage divider circuit 160 that connects to a 2-position dipswitch 164. The voltage divider circuit 160 includes a plurality of resistors R2, R22, and R23. With the two-position dip switch 164 being set to provide four different values, the voltage divider circuit 160 can therefore generate four specific voltage output values. The voltage output of the voltage divider circuit 160 is then fed to an A/D input port PB7168 of the MCU 108. In this way, output values of the voltage divider 160 are sampled to obtain a plurality of operating ranges of the pump 116. Furthermore, an operating hydraulic pressure range of the pump control system 100 can be pre-determined and set. In one construction, there are eight ranges. These ranges are between 20 and 40 (or 30) lb/in2, between 30 and 50 (or 40) lb/in2, between 40 and 60 (or 50) lb/in2, and between 50 and 70 (or 60) lb/in2.
A feedback differential pressure tuner 172 is also coupled to the MCU 108 and is configured to fine-tune a feedback differential pressure to a desired pressure level. Specifically, the feedback differential pressure tuner 172 includes a second voltage divider 176 arranged with a plurality of capacitors, and a second 2-position dipswitch 180. Depending on how the second 2-position dipswitch 180 is set, different levels of electrical signals are generated. As a result, the feedback differential pressure can range between 10 lb/in2 and 20 lb/in2. Furthermore, the feedback differential pressure tuner 172 also includes a fifth potentiometer 184 that can be adjusted to tune a maximum water pressure range to 50 lb/in2 and 70 lb/in2. In this way, with an increment step of X between 0 lb/in2 and 19 lb/in2, the pressure range is between 50+X lb/in2 and 70+X lb/in2.
Furthermore, the display unit 128 includes a plurality of indicators or LED's 200, a digital display 204, and a drive circuit 208. The display unit 128 uses the LED's 200 to display a plurality of operating status of the control system 100 and the pump 116. In one construction, there are six LED's in the display unit 128 to indicate a low-water status detected by the system, an overload status, a rapid-cycle status, an undervoltage status, and an overvoltage status.
The pump control system 100 also includes a reset button K1212 and a set button K2216 for setting or resetting the pump control system 100 under conditions such as system failure, low-water alarm, and overload alarm. During the setting or the resetting process, the LED's 200a, 200b will flash for the low water alarm and the overload conditions, while the LED 200d will indicate an alarm threshold value.
In some constructions, after pressing K1212 and holding for a short period of time, such as 2 seconds, the system 100 will enter into a phase angle setup mode. The overload indicator light 200b flashes while the display 204 shows a factory set overload phase angle protection value. The phase angle will reduce 1 degree by pressing K2216 once. The phase angle will reduce continuously at a 2 Hz rate by pressing and holding K2216 until the required value is reached. Pressing K1212 again, the low water indicator light 200a flashes while the display 204 shows the factory set low water protection value. The phase angle will increase 1 degree by pressing K2216 once. The phase angle will increase continuously at a 2 Hz rate by pressing and holding K2216 until the required value is reached. Pressing K1212 again exits the setup mode.
The POR circuit 408 includes components such as dynatron 432, resistors, and capacitors. The POR circuit 408 generates reliable signals in order to ensure that the MCU 108 works normally under abnormal conditions, such as a low voltage reset. The power supply voltage detecting circuit 424 includes components such as potentiometer 436, resistors R9440 and R6444, and a Zener diode 448 parallel to a capacitor C3452 and the resistor R6444. An analog-to-digital module of the MCU 108 is also configured to convert the analog differential pressure voltage sensed by the amplifying module 104 into a digital differential pressure voltage. The MCU 108 compares the digital differential pressure voltage with a high voltage alarm threshold value and a low voltage alarm threshold value to ensure that the pump 116 operates within a pre-determined range, and to protect the pump motor from damages by overcurrent, overvoltage, or undervoltage. Therefore, adjusting or tuning the potentiometer W6436 allows the reference threshold values of the high and low voltages to be adjusted. Furthermore, the crystal oscillating circuit 428 includes components such as a 4 MHz oscillator OSC 452 parallel to a resistor R1454 and capacitors C1456 and C2458. The crystal oscillating circuit 428 provides a standard high frequency clock-pulse signal for the operation of sequential circuitry of the MCU 108.
In some constructions, adjusting potentiometer 436 slightly clockwise reduces the power supply nominal voltage that is typically set at 230 VAC. In this way, the operating voltage range can be lowered. However, to raise the operating voltage range, the potentiometer 436 is adjusted slightly counter-clockwise to increase the power supply nominal voltage. In general, adjusting the potentiometer 436 does not alter the minimum specification for pump operation, for example, about −15% to stop pump and about −10% automatic reset for the under voltage protection, about +15% to stop pump and about +10% automatic reset for over voltage protection.
In one construction, the MCU 108 is programmed to turn the solid state relay driver 420 and the LED's 200 on and off in response to different control signals. The MCU 108 also includes internal clock circuits for performing the various timing functions. Although the MCU 108 is a micro-controller in the pump control system 100, other types of devices such as a microprocessor or an application specific integrated circuit (“ASIC”) can also be used.
An analog water pressure signal from the amplifying module 104 is fed into the A/D conversion port 168 of MCU 108 through the operational amplifier circuit 144. The MCU 108 will determine the water pressure condition according to the detecting A/D value. The two-position dip switch 164, and a one position dip switch on the system 100 allows the pressure range to be preset to one of eight ranges: 20-40 pounds per squared inch (lb/in2), 30-50 lb/in2, 40-60 lb/in2, 50-70 lb/in2, 20-30 lb/in2, 30-40 lbs/in2, 40-50 lb/in2, and 50-60 lb/in2. In addition, the adjustable potentiometer W5 can adjust the working range between 50-70 lbs/in2 and 50-60 lbs/in2 to (50+X)-(70+X) lbs/in2 and (50+X)-(60+X) lbs/in2 where X is between 0 and 19 lbs/in2. The overvoltage or undervoltage circuit functions to generate overvoltage or undervoltage signals for the MCU 108, and for the overvoltage or undervoltage LEDs. Furthermore, the power supply transformer 404 functions to lower the voltage to a value more suited for the system.
The operation of the pump control and protection system 100 is summarized by the following examples. For example, during normal operation of the pump 116, power from the power supply is provided to the system 100. Once the system 100 has been reset, the MCU 108 resets, and the LED 200f is off. If the MCU 108 only detects a low water pressure signal from the amplifying module 104, the relay and the LED 200f are switched on, and thus activates the pump 116. However, if the MCU 108 only detects a high water pressure signal, the relay and the LED 200f are switched off, and thus deactivates the pump 116.
For another example, when the MCU 108 detects a low water condition, such as when the pump 116 is underloaded, the relay is turned off. Once the relay has been turned off, a timer with a specific amount of time delay will be set, and the LED 200a is lit. Once the amount of time delay has elapsed, the relay is switched back on. Furthermore, if the MCU 108 detects that the water pressure is high, the relay is switched off, the LED 200a is turned off, and the system 100 returns to a normal operating condition. Otherwise, if an idle condition persists, the relay is switched off, and a timer with a delay time is set. Once the delay time has elapsed, the relay is switched on.
For another example, if the MCU 108 detects that the pump 116 has been overloaded, the LED 200b is lit, and the relay is switched off until the MCU 108 has been reset. However, if the MCU 108 detects an overvoltage or undervoltage from the pump 116, the relay is switch off, either the LED 200d or the LED 200e is lit, respectively, until the voltage phase detector detects normal level of voltage is supplied.
Additional functions of the pump control and protection system 100 is summarized by the following examples.
The analog water pressure signal is loaded to the A/D converter port of the MCU 160 through a linear operational amplifier. The MCU 108 examines or determines a state of water pressure based on an A/D value, and allows the pressure range to be preset at one of the eight ranges through the 2-position dip switch 164 and 1-position dip switch of the system 100. Furthermore, adjusting potentiometer 184 adjusts a differential pressure fed to the MCU 108, thereby controlling maximum water supply pressure operating ranges at 50-70 lb/in2 and 50-60 lb/in2 via an internal conversion routine. With an adjustment range X between 0 and 19 lb/in2, the converted operating range is therefore (50+X)-(70+X) lb/in2 and (50+X)-(60+X) lb/in2.
The feedback differential pressure circuit 172 includes resistors R7, and R51, capacitor C30, and switch 180. Depending on the dipswitch position, which is either “ON” or “OFF,” a high or low logic level is generated. With these logic levels, the system 100 can choose a differential pressure between 10 lb/in2 and 20 lb/in2.
The system 100 has an operation for regulating the phase of an electric motor, as to be applied to different phase characteristics with different load conditions. The operator presses K2216 to set the lower limit phase angle, and presses K1212 to regulate the alarm phase angle. The operator presses K2216 again to set a higher limit phase angle, and presses K1212 to regulate the alarm phase angle. The operator presses K2216 again to confirm and save the setting values.
Adjusting the potentiometer 154 can regulate the magnified signal of pressure transducer. Adjusting the second and the third potentiometers 150, 152 can regulate the linearity of the pressure transducer signal. While the “zero” value of the pressure transducer can be regulated through adjusting the fourth potentiometer 136. Thus, the circuit can use different types of transducers.
Pressing K2216 and K1212 regulates the motor alarm phase threshold values, which also can be seen through the LED display 200. A data set will be stored in a FLASH ROM of the MCU 108 and will not be lost during a power outage. The over/under voltage alarm threshold value is set by way of software, and can be adjusted by the potentiometer 184.
The pump control system 100 may connect to a three-phase pump 504 with a junction box 508. Junction box 508 can be applied to a three-phase pump motor with different inputs, since the motor may include an overcurrent protector that can set an operating current, a thermal relay with phase-lock protection, and an AC contactor controlled by a solid state relay in the pump protector.
Various features and advantages of the invention are set forth in the following claims.
This application claims the benefit of U.S. Patent Application No. 60/575,136, titled “Pump Control,” filed on May 28, 2004, the entire content of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US04/24905 | 7/30/2004 | WO | 00 | 11/29/2007 |
| Number | Date | Country | |
|---|---|---|---|
| 60575136 | May 2004 | US |
