High efficiency circulator with sensors
A highly efficient circulator system is provided, useful for hydronic systems, including both heating and cooling systems. The stand-alone circulator motor is controllable by input from certain sensors, preferably thermal sensors, which provide data enabling the controller of the brushless pump motor to vary its flow output to meet changes in systems loads. The circulator has a ceramic permanent magnet rotor, such as a ferrite, with an electronically, preferably sinusoidally, commutated, electro-magnetic stator controlling the input of electrical power.
1 . A stand-alone, wet rotor circulator comprising:
a centrifugal impeller configured to move a hydronic fluid through a recirculating hydronic fluid system;
a variable frequency DC motor operationally connected to the impeller to drive the impeller, the DC motor comprising:
a permanent magnet rotor formed of a ferrite ceramic magnet material, and
a system of stator coils configured to be powered by a sinusoidally variable DC current;
a rectifier system configured to convert an AC current to a non-stepped down DC current, the rectifier system including:
a first electrical circuit connection configured to connect the rectifier system to an AC current source, and
a second electrical circuit connection configured to output the non-stepped down DC current from the rectifier system; and
an electronic motor control system electrically connected to the second electrical circuit connection, the electronic motor control system comprising:
a power module configured to convert the non-stepped down DC current from the rectifier system to an artificial sinusoidally variable frequency DC current output,
an electronic variable frequency drive (VFD) electrically connected to the power module and configured to receive the artificial sinusoidally variable frequency DC current output, the VFD being configured to receive data signals from at least one thermal sensor, and
a third electrical connection electrically connecting the electronic motor control system to the system of stator coils of the DC motor,
wherein the VFD is configured to control a speed of the DC motor by varying the a frequency of the artificial sinusoidally variable frequency DC current output powering the system of stator coils of the DC motor in response to the data signals received from the at least one thermal sensor, and thereby control a speed of the impeller and resulting flow of the hydronic fluid in through the recirculating hydronic fluid system.
2 . The stand-alone, wet rotor circulator of claim 1 , wherein the variable frequency DC current output has a voltage in a range of from about 160 Volts to about 350 Volts.
3 . The stand-alone, wet rotor circulator of claim 1 , wherein the electronic motor control system further comprises:
a first printed circuit board configured to receive and rectify the AC current and to receive and interpret the data signals from the at least one thermal sensor, and
a second printed circuit board configured to control the speed of the DC motor by varying the frequency of the sinusoidally variable frequency DC current output powering the stator coils;
wherein the second printed circuit board comprises a microcontroller configured to interpret the data signals received from the at least one thermal sensor via the first printed circuit board, and to control a fluid flow rate of the hydronic fluid based on the data signals.
4 . The stand-alone, wet rotor circulator of claim 1 , wherein the rectifier system further comprises a bridge rectifier and a capacitor.
5 . The stand-alone, wet rotor circulator of claim 1 , wherein the power module comprises a three-phase inverter configured to be controlled by a microcontroller to convert the non-stepped down DC current from the rectifier system to the artificial sinusoidally variable frequency DC current output.
6 . The stand-alone, wet rotor circulator of claim 1 , wherein the VFD comprises an operational amplifier (“OP AMP”), a comparator, and a resonator, configured to be controlled by a microcontroller to interpret and act upon the data signal from the at least one thermal sensor to control the artificial sinusoidally variable frequency DC current output to directly set the speed of the DC motor required to meet the hydronic fluid flow demands of the recirculating hydronic fluid system.
7 . The stand-alone, wet rotor circulator of claim 1 , further comprising a housing for the DC motor, the housing containing:
the permanent magnet rotor;
the system of stator coils;
a microcontroller;
a power control printed circuit board (PCB) directly connected to the AC current source and configured to output the non-stepped down DC current; and
a motor control PCB electrically connected to receive the non-stepped down DC current from the power control PCB and directly connected to the system of stator coils of the DC motor.
8 . The stand-alone, wet rotor circulator of claim 1 , wherein the electronic motor control system further comprises an electronic commutation system electrically connected to the power module and configured to receive the artificial sinusoidally variable frequency DC current output and output the artificial sinusoidally variable frequency DC current output to the system of stator coils.
9 . The stand-alone, wet rotor circulator of claim 1 , further comprising:
manually operable controls for selecting a specific program to operate the wet rotor circulator in accordance with requirements of the hydronic fluid system;
an LCD screen configured for displaying indications of the specific program selected; and
electronic connections between the manually operable controls, a first printed circuit board, and the LCD screen.
10 . The stand-alone, wet rotor circulator of claim 9 , wherein the specific program operates the VFD to maintain a designated temperature differential between an outlet of a hydronic fluid source and a return line of the hydronic fluid source.
11 . The stand-alone, wet rotor circulator of claim 9 , wherein the recirculating hydronic fluid system includes a boiler, and wherein the specific program operates the VFD to prevent the hydronic fluid from returning to the boiler at a temperature below a predetermined temperature of the hydronic fluid.
12 . The stand-alone, wet rotor circulator of claim 11 , wherein one of the at least one thermal sensor is disposed at a return to the boiler, and wherein the specific program operates the VFD to reduce the flow of the hydronic fluid so as to return a lower volume of the hydronic fluid to the boiler until a space to be heated reaches a predetermined temperature.
13 . A method of operating a stand-alone, wet rotor circulator to circulate hydronic fluid through a hydronic fluid circulation system, the method comprising:
providing a variable frequency DC motor including a system of stator coils and a rotor operationally connected to a centrifugal impeller to drive the centrifugal impeller;
receiving, at a rectifier system, an AC current from an AC current source;
converting, with the rectifier system, the AC current to a non-stepped down DC current;
receiving, at an electronic motor control system, the non-stepped down DC current from the rectifier system;
converting, at a power module of the electronic motor control system, the non-stepped down DC current to an artificial sinusoidally variable frequency DC current output;
receiving, at an electronic variable frequency drive (VFD) of the electronic motor control system, one or more data signals from at least one thermal sensor;
controlling, via the VFD, a speed of the DC motor by varying a frequency of the artificial sinusoidally variable frequency DC current output that is transmitted to a system of stator coils of the DC motor, the varying of the frequency being in response to the one or more data signals from the at least one thermal sensor, wherein the rotor rotates at varying speeds in response to the varying frequency of the artificial sinusoidally variable frequency DC current output transmitted to the system of stator coils, thereby controlling circulation of the hydronic fluid through the hydronic fluid circulation system.
14 . The method of claim 13 , wherein the variable frequency DC current output has a voltage in a range of from about 160 Volts to about 350 Volts.
15 . The method of claim 13 , wherein the electronic motor control system further comprises a first printed circuit board (PCB) and a second PCB including a microcontroller, the method further comprising:
receiving and rectifying the AC current with the first PCB;
receiving data from the at least one thermal sensor with the first PCB;
receiving, via the microcontroller, the data from the at least one thermal sensor;
based on the data from the at least one thermal sensor, controlling, via the second PCB, the speed of the DC motor by varying a voltage change frequency of the sinusoidally variable DC current output powering the stator coils to control a fluid flow rate of the hydronic fluid.
16 . The method of claim 13 , wherein the rectifier system further comprises a bridge rectifier and a capacitor.
17 . The method of claim 13 further comprising:
receiving a selection of a specific program to operate the wet rotor circulator in accordance with requirements of the hydronic fluid system; and
displaying, via an LCD screen, one or more indications of the specific program selected.
18 . The method of claim 17 further comprising operating the VFD based on the specific program selected to maintain a designated temperature differential between an outlet of a hydronic fluid source and a return line of the hydronic fluid source.
19 . The method of claim 17 , wherein the recirculating hydronic fluid system includes a boiler, and wherein the method further comprises operating the VFD based on the specific program selected to prevent the hydronic fluid from returning to the boiler at a temperature below a predetermined temperature of the hydronic fluid.
20 . The method of claim 19 , wherein one of the at least one thermal sensor is disposed at a return to the boiler, and wherein the method further comprises operating the VFD based on the specific program selected to reduce a flow of the hydronic fluid so as to return a lower volume of the hydronic fluid to the boiler until a space to be heated reaches a predetermined temperature.