High efficiency circulator with sensors

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.