Apparatuses, systems, and methods of variable frequency drive operation and control

#The present application relates generally to apparatuses, systems, and methods of variable frequency drive operation and control. Variable frequency motor drives offer a number of potential benefits for applications such as driving compressors or other loads for heating, ventilation, air-conditioning, or refrigeration (HVACR) systems, including potential for enhanced efficiency, power density, and speed control precision. Such motor drives present unique challenges with respect to waste heat and control of the same. Conventional designs often seek to minimize waste losses under all operating conditions to the extent possible in light of other operational targets. Some proposals have been made for recapture of part of the waste heat generated by variable frequency drive operation. These approaches suffer from a number of disadvantages and shortcomings including those respecting control and beneficial use of waste heat. Such motor drives also present unique challenges with respect to audible noise and control of the same. Conventional designs often seek to minimize audible noise under all operating conditions, for example by setting the switching frequency as high as the motor load will allow. These approaches suffer from a number of disadvantages and shortcomings including those respecting system efficiency and generation of waste heat. There remains a significant need for the unique and inventive apparatuses, methods and systems disclosed herein.

#For the purposes of clearly, concisely and exactly describing exemplary embodiments of the invention, the manner and process of making and using the same, and to enable the practice, making and use of the same, reference will now be made to certain exemplary embodiments, including those illustrated in the figures, and specific language will be used to describe the same. It shall nevertheless be understood that no limitation of the scope of the invention is thereby created, and that the invention includes and protects such alterations, modifications, and further applications of the exemplary embodiments as would occur to one skilled in the art.

#A number of non-limiting exemplary embodiments are summarized below. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

#FIG. 1 is a schematic illustration of an exemplary HVACR system having a waste heat recovery circuit.

#FIG. 2 is a schematic illustration of an exemplary variable frequency drive and permanent magnet motor.

#FIG. 3 is a schematic illustration of the inverter module of the system of FIG. 2.

#With reference to FIG. 1 there is illustrated an exemplary HVACR system 100 which includes a refrigerant loop comprising a compressor 110, a first heat exchanger 120, an expander 125, and a second heat exchanger 130. HVACR system 100 may further comprise a reversing mechanism configured to reverse the flow direction of the working fluid. In the present embodiment, the reversing mechanism is illustrated as four-way valve 140. It is also contemplated that other reversing mechanisms may be utilized, such as separate two-way valves. Furthermore, in certain exemplary embodiments such as large chiller units, it is contemplated that the compressor 110 may be directly in flow series with second heat exchanger 130 and first heat exchanger 120, and the valving which permits the system to operate in reverse, i.e., as a heat pump and a cooler, may be omitted. In such embodiments first heat exchanger 120 may be configured as a dedicated condenser and second heat exchanger 130 may be configured as a dedicated evaporator.

#Four-way valve 140 is configured to receive compressed refrigerant from compressor 110 and direct the compressed refrigerant to either first heat exchanger 120 or second heat exchanger 130. Four-way valve 140 has a first configuration in which refrigerant lines are connected as shown by the solid lines and refrigerant flows in the direction of the solid arrows, and a second configuration in which refrigerant lines are connected as shown by the dashed lines and refrigerant flows in the direction of the dashed arrows. First heat exchanger 120 is a condenser when the flow is in the direction of the solid arrows, and an evaporator when the flow is in the direction of the dashed arrows. Second heat exchanger 130 is an evaporator when flow is in the direction of the solid arrows, and a condenser when flow is in the direction of the dashed arrows. The following description will be made with reference to HVACR system 100 when four-way valve 140 is in the first configuration, corresponding to solid lines and arrows. One having skill in the art will readily understand that HVACR system 100 operates in a similar fashion when four-way valve 140 is in the second configuration.

#In the first configuration of four-way valve 140, refrigerant flows through system 100 in a closed loop from compressor 110 to first heat exchanger 120 to expander 125 to second heat exchanger 130 and back to compressor 110. A waste heat recovery circuit 180 transfers heat generated by variable frequency drive 155 to second heat exchanger 130. Variable frequency drive 155 may be a variable frequency motor drive 200 (FIG. 2) having an inverter module 280, described below. Various embodiments of system 100 may also include additional refrigerant loop elements including, for example, valves for controlling refrigerant flow, refrigerant filters, economizers, oil separators and/or cooling components and flow paths for various system components.