High efficiency hydronic circulator with sensors

Abstract

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.

What is claimed is: 
     
         1 . In a stand-alone, wet rotor circulator for a hydronic system, the circulator comprising a centrifugal impeller and an electrically-powered variable frequency DC motor operationally connected to the centrifugal impeller to drive the impeller, the variable frequency DC motor comprising a permanent magnet rotor and a system of stator coils powered by a variable DC current; an electronic control system, electrically connected to the stator coils of the motor, the electronic system comprising a rectifier, for rectifying AC current to DC current, an electronic commutation system and an electronic variable frequency drive (“VFD”) control system, for controlling the speed of the motor by producing an artificial variable voltage frequency for the rectified DC current from the rectifier, for powering the pump motor, an electrical data signal connection to receive data signals reflecting the output of a thermostatic sensor, an operational connection from the electrical data signal connection to the VFD to pass any data signals to the VFD, and an electrical circuit connection between the rectifier portion of the control system and a source of AC current;
 the improvement comprising: the permanent magnet rotor being formed of a ferrite magnet; the rectified DC voltage being maintained at the native voltage of the AC current, and an IGBT power module for converting the DC current to a sinusoidally varying DC voltage from a rectified AC power supply, controlled by the VFD, for powering the stator coils; the VFD system varying the frequency of the sinusoidally variable current in response to changes in system loads, as signaled by the data signal from at least one thermal sensor; the electronic commutation system working in conjunction with the VFD to control the speed of the electrically powered motor, so as to result in a highly efficient and substantially noise-free motor. 
 
     
     
         2 . In the stand-alone, wet rotor circulator system for the hydronic system of  claim 1 , wherein the variable frequency DC current has a voltage in the range of from about 160 Volts to about 350 Volts; 
     
     
         3 . In the stand-alone, wet rotor circulator system for the hydronic system of  claim 1 , the electronic system comprising two printed circuit boards, one printed circuit board for receiving and rectifying AC line current and for receiving and interpreting data from at least one thermostatic sensor, and a second printed circuit board for controlling the motor speed by varying the voltage change frequency of the power to the stator; wherein the second printed circuit board comprises a microcontroller, which interprets the thermal data received from the thermal sensor via the first printed circuit boards, and controls the pump operation to maintain the necessary fluid flow rate of the hydronic fluid based upon such thermal data. 
     
     
         4 . In the stand-alone, wet rotor circulator system for a hydronic system of  claim 2 , further comprising connections attached to the first printed circuit board for selecting a specific program for controlling the operation of the hydronic circulator. 
     
     
         5 . In the stand-alone, wet rotor circulator system for a hydronic system of  claim 3 , further comprising manually operable controls for selecting a specific program to operate the pump in accordance with the requirements of the hydronic system; an LCD screen for displaying indications of the program selected; and connections between the manually operable controls and the first printed circuit board and the LCD screen. 
     
     
         6 . In the stand-alone, wet rotor circulator system for the hydronic system of  claim 4 , wherein the program operating the VFD acts to maintain a designated temperature differential between the outlet from the hydronic fluid source and the return line to the hydronic fluid source. 
     
     
         7 . In the stand-alone, wet rotor circulator system for the hydronic system of  claim 4 , wherein the hydronic system includes a boiler, and wherein the program operating the VFD acts to prevent the return of hydronic fluid to the boiler at a temperature below that necessary to prevent interference with the proper operation of the boiler or to prevent damage to the boiler. 
     
     
         8 . In the stand-alone, wet rotor circulator system for the hydronic system of  claim 7 , comprising a thermistor located at the return to the boiler, and wherein the program controlling the VFD acts to slow down the flow of hydronic fluid so as to return a smaller amount of fluid to the boiler until the space to be heated is warned up to the point where the returning fluid will not cause damage to the boiler. 
     
     
         9 . In the stand-alone, wet rotor circulator system for the hydronic system of  claim 7 , comprising a thermistor located at the return to the boiler, and wherein the program controlling the VFD acts to slow down the flow of hydronic fluid so as to return a smaller amount of fluid to the boiler until the space to be heated is warned up to the point where the returning fluid will not cause damage to the boiler.