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.

Application of Active Gate Driver in Variable Frequency Drives

Abstract: This paper presents the results of an investigation into using a commercially available active gate driver integrated circuit (IC) in variable frequency drive (VFD) applications. The gate driver provides multiple steps of gate current levels to control the gate charge of insulated-gate bipolar transistors (IGBTs) during turn-on transitions to adjust dVce/dt, dic/dt and turn-on energy loss. This provides a means for optimizing switching losses, reverse recovery current of the freewheeling diode, and EMI emissions. Experimental results are provided to demonstrate the advantages over a conventional fixed-resistance gate driver. Preliminary simulation results are provided to illustrate the benefits for IGBT junction temperature reduction.

Controls and operation of variable frequency drives

Abstract: Unique apparatuses, methods, and systems of opposing, limiting, and/or preventing undesired or un-commanded compressor rotation are disclosed. One exemplary embodiment is an HVACR system comprising a variable frequency drive configured to drive an electric motor to rotate a screw compressor or scroll compressor. A controller is configured to monitor various aspects of the system and to control the drive. When a condition indicative of potential undesired or un-commanded compressor rotation is identified, the controller commands the variable frequency drive to control the motor to limit and preferably prevent compressor rotation. One technique comprises shorting switches of the drive to a DC bus rail to allow back EMF induced current in the motor windings to be dissipated through winding resistance thus providing a damping force. Another technique comprises controlling the inverter to insert a DC current into the motor to cause the motor to align to and hold a particular position.

Control of Variable Frequency Drive PWM to Mitigate Motor Overvoltage Due to Double Pulsing in Reflected Wave Phenomenon

Abstract: It is well understood that variable frequency drives (VFDs) can cause overvoltage up to twice the DC bus voltage (2 pu, where 1 per unit is the DC bus voltage) at the machine winding terminals, especially if long power cables are used and/or fast rise and fall times are implemented. If the voltage oscillation is not fully decayed when the next pulse arrives, double pulsing occurs and the overvoltage can go up to 4 pu in one switching event. To prevent the damage of the 4 pu overvoltage to the electric machine insulation system, filters are commonly used between the VFD and the machine. The filters, however, add significant cost and size to the system. The higher dv/dt associated with the increasingly popular wide-bandgap devices requires even larger and more expensive filters to be installed. This paper proposes a new PWM control method, the double pulsing offset technique (DPOT), to restrain the overvoltage peak-to-peaks within 2 pu regardless of the switching frequency or dV/dt of the power semiconductor devices. The need to install filters, therefore, is potentially eliminated with the implementation of DPOT. This control scheme was validated using an accurate reflected wave phenomenon simulation model using finite element analysis (FEA). It was also fully implemented online and offline using a DSP and a SiC-MOSFET -based inverter. The experimental results with various operating conditions of the inverter are presented and analyzed. The results show that DPOT is successful in eliminating double pulsing even in harsh operating conditions such as high dV/dt, long cable length, and frequent polarity reversals.

MODELING a transistor converter-fed permanent magnet poly-phase machine and a variable-frequency drive controller under non-sinusoidal back-EMF conditions

Abstract: The paper presents a model of a poly-phase permanent magnet motor of the marine propulsion drive energized by multistage VSI. The model defines more precisely the non-sinusoidal waveform of back-EMF and its impact on the current distortion and electromagnetic torque ripples. The paper concludes by analyzing simulation results that have shown significant suppression of high order current harmonics and corresponding decrease in torque ripples due to the proposed control algorithm realized in a phase reference frame.

Intelligent power module

Abstract: An intelligent power module includes a rectifying circuit for connecting with a corresponding external AC power source to convert a first AC power transmitted from the external AC power source into afirst DC power; An inverter circuit connected to the rectifier circuit for converting the first direct current into a second alternating current; A control circuit and a driving circuit are connectedbetween the inverter circuit and the control circuit for driving the inverter circuit to operate under the control of the control circuit. As the intelligent pow module controls the circuit, rectifiercircuit, the inverter circuit and the driving circuit are integrated in the whole module, Compared with the existing intelligent power module, the intelligent power module has a higher integration level, which simplifies the hardware circuit design, helps to shorten the development cycle and reduce the volume of the system. Users only need to build a simple peripheral circuit to complete the development of the variable frequency drive system.