Pump controller
First Claim
1. A method of controlling an electric motor pump, the method comprising:
- providing an AC power signal having a positive half cycle and a negative half cycle;
measuring the voltage of the AC power signal and generating a first two-state output signal that is in a logic high state when the measured voltage is on the positive half cycle and is in a logic low state when the measured voltage is on the negative half cycle;
measuring the current of the AC power signal and generating a second two-state output signal that is in logic high state when the measured current is on the positive half cycle and is in a logic low state when the measured current is on the negative half cycle;
determining a phase difference based on a time difference between the first two-state output signal and the second two-state output signal;
comparing the phase difference to a predetermined threshold value;
opening a switch if the determined phase difference is equal to or greater that the predetermined threshold value; and
closing the switch after a predetermined amount of time has elapsed.
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Accused Products
Abstract
A method and apparatus for controlling an electric motor pump. The method includes the acts of providing an AC power signal having a positive half cycle and a negative half cycle, measuring the voltage of the AC power signal and generating a first two-state output signal that is in a logic high state when the measured voltage is on the positive half cycle and that is in a logic low state when the measured voltage is on the negative half cycle, and measuring the current of the AC power signal and generating a second two-state output signal that is in logic high state when the measured current is on the positive half cycle and that is in a logic low state when the measured current is on the negative half cycle. The method also includes determining a time difference between the first and second two-state output signals, calculating a phase difference based on the time difference, comparing the phase difference to a predetermined threshold value, opening a switch if the determined phase difference is equal to or greater that the predetermined threshold value, and, after the switch is opened, closing the switch after a predetermined amount of time has elapsed.
The invention may be implemented in an apparatus that includes a voltage filter capable of being coupled to an AC power source and of generating a first two-state output signal, a current filter capable of being a coupled to an AC power source and of generating a second two-state output signal, a power supply circuit capable of producing a DC power signal, a programmable device coupled to the voltage filter, the current filter, and the power supply circuit and operable to produce a control signal based on the time difference between the first and second two-state output signals, and a switch coupled to the programmable device and operable to open in response to the control signal.
54 Citations
28 Claims
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1. A method of controlling an electric motor pump, the method comprising:
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providing an AC power signal having a positive half cycle and a negative half cycle;
measuring the voltage of the AC power signal and generating a first two-state output signal that is in a logic high state when the measured voltage is on the positive half cycle and is in a logic low state when the measured voltage is on the negative half cycle;
measuring the current of the AC power signal and generating a second two-state output signal that is in logic high state when the measured current is on the positive half cycle and is in a logic low state when the measured current is on the negative half cycle;
determining a phase difference based on a time difference between the first two-state output signal and the second two-state output signal;
comparing the phase difference to a predetermined threshold value;
opening a switch if the determined phase difference is equal to or greater that the predetermined threshold value; and
closing the switch after a predetermined amount of time has elapsed. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An pump control apparatus comprising:
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a voltage filter capable of being coupled to an AC power source and of generating a first two-state output signal;
a current filter capable of being a coupled to an AC power source and of generating a second two-state output signal;
a power supply circuit capable of producing a DC power signal;
a controller coupled to the voltage filter, the current filter, and the power supply circuit and operable to produce a control signal based on the time differential between the first and second two-state output signals; and
a switch coupled to the controller and operable to open in response to the control signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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18. A pump comprising:
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a housing;
a motor positioned within the housing;
a control module positioned with the housing, the control module including a voltage filter capable of being coupled to an AC power source and of generating a first two-state output signal;
a current filter capable of being a coupled to an AC power source and of generating a second two-state output signal;
a power supply circuit capable of producing a DC power signal;
a programmable device coupled to the voltage filter, the current filter, and the power supply circuit and programmed to produce a control signal based on the time differential between the first and second two-state output signals; and
a switch coupled to the programmable device, operable to open in response to the control signal, and having a semiconductor device coupled in parallel to a second switching device.
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Specification