Variable-frequency drive

About: Variable-frequency drive is a research topic. Over the lifetime, 837 publications have been published within this topic receiving 5691 citations. The topic is also known as: VFD.

Photovoltaic integrated variable frequency drive

Abstract: A photovoltaic (PV) integrated variable frequency drive system having a variable frequency drive and an energy source. The variable frequency drive having a back end inverter, a DC bus electrically connected to the back end inverter, and an active front end electrically connected to the DC bus to facilitate bi-directional power flow to and from a power grid. The energy source being electrically connected to the DC bus.

Engine driven power inverter system with cogeneration

Abstract: A combined heat and AC power generating system is disclosed having black start capability for the full time, simultaneous production of both electricity and heat. Heat generated within the system is captured and used for heating applications such as heating building air and tap water. The power generating system comprises an engine, generator, rectifier, variable frequency drive inverter, and inverter control electronics. The system provides improved efficiency and prolonged engine life by always operating the engine with its throttle fully open to obtain maximum efficiency and the engine is normally operated near its stall point. In this operating state the inverter control electronics adjust the power output from the inverter to control the speed of the engine. This is done by increasing the power output from the inverter when the power drawn by the load decreases. This causes the engine to operate closer to its stall point and it slows down. The power from the inverter is decreased when the power drawn by the load increases. This causes the engine to operate further from its stall point and it speeds up., The slight power changes to facilitate this operation will always be drawn from or distributed to the electric utility grid so there is no wasted power. The inverter control electronics are responsive to signals from loads such as refrigeration loads to cause the frequency of the inverter output to change to permit the refrigeration load to operate more efficiently.

Power Line Considerations for Variable Frequency Drives

Abstract: More frequent use of variable frequency drives requires that the interaction between the drives and the power line be considered in order to avoid undesirable power line effects caused by the drive. In addition, the power line characteristics need to be defined by the drive manufacturer which assure proper operation of the variable frequency drive. The potential effects the drive has on the power line is discussed, including line harmonics, line notching, and line noise. General approaches for minimizing effects and installation guidelines are also reviewed.

Energy reduction process and interface for open or closed loop fluid systems with or without filters

Abstract: A Process and Interface to reduce the energy required to operate a swimming pool pump. The process improves the conventional process by causing the pump to vary its operation based on variable filter loading conditions. The process uses a flow sensor to send a signal to the interface which then signals a variable frequency drive to increase or decrease the speed of the pump motor in compliance with user programmed flow. The pump operates at reduced energy until the filter load increases due to captured debris. As the filter load increases, the pump speed increases.

Energy Savings Potential for Pumping Water in District Heating Stations

Abstract: In district heating stations, the heat carrier is circulated between the energy source and consumers by a pumping system. Fluid handling systems, such as pumping systems, are responsible for a significant portion of the total electrical energy use. Significant opportunities exist to reduce pumping energy through smart design, retrofitting, and operating practices. Most existing systems requiring flow control make use of bypass lines, throttling valves or pump speed adjustments. The most efficient of these options is pump speed control. One of the issues in using variable-speed pumping systems, however, is the total efficiency of the electric motor/pump arrangement under a given operating condition. This paper provides a comprehensive discussion about pump control in heating stations and analyzes the energy efficiency of flow control methods. Specific attention is also given to the selection of motor types, sizing and pump duty cycle. A comparative energy analysis is performed on the hot water discharge adjustment using throttling control valves and variable-speed drives in a district heating station constructed in Romania. To correlate the pumped flow rate with the heat demand and to ensure the necessary pressure using minimum energy, an automatic system has been designed. The performances of these control methods are evaluated in two practical applications. The results show that approximately 20%–50% of total pumping energy could be saved by using the optimal control method with variable-speed pumps. Additionally, some modernization solutions to reduce the environmental impact of heating stations are described.