Electronic filter

About: Electronic filter is a research topic. Over the lifetime, 13207 publications have been published within this topic receiving 93063 citations. The topic is also known as: filter.

Filter networks for long cable drives and their influence on motor voltage distribution and common-mode currents

Abstract: Filter networks for long cable drives have been studied in the last decade to solve the over-voltage problem at the motor terminals. However, little research has been dedicated to analyze their influence on the voltage distribution in the motor stator winding and on the circulation of the common-mode currents. In this paper, the project of dv/dt filters through simulation and analysis from previous works is extended including the motor voltage distribution and common-mode current analysis. Simulation and experimental results are presented demonstrating the usefulness of the filter networks on the motor over-voltage mitigation. Three filter topologies is discussed and compared here: RLC filter at the motor terminals, RLC Filter at the inverter output and reactor filter, which is extensively used in the industry. Simulation and experimental results demonstrates that the RLC Filter at the inverter output is the most interesting solution among the main types of passive filter networks.

RF MEMS Switches and Integrated Switching Circuits

Abstract: Radio frequency (RF) microelectromechanical systems (MEMS) have been pursued for more than a decade as a solution of high-performance on-chip fixed, tunable and reconfigurable circuits. This paper reviews our research work on RF MEMS switches and switching circuits in the past five years. The research work first concentrates on the development of lateral DC-contact switches and capacitive shunt switches. Low insertion loss, high isolation and wide frequency band have been achieved for the two types of switches; then the switches have been integrated with transmission lines to achieve different switching circuits, such as single-pole-multi-throw (SPMT) switching circuits, tunable band-pass filter, tunable band-stop filter and reconfigurable filter circuits. Substrate transfer process and surface planarization process are used to fabricate the above mentioned devices and circuits. The advantages of these two fabrication processes provide great flexibility in developing different types of RF MEMS switches and circuits. The ultimate target is to produce more powerful and sophisticated wireless appliances operating in handsets, base stations, and satellites with low power consumption and cost.

Multi-band high-frequency circuit, multi-band high-frequency circuit component and multi-band communication apparatus using same

Abstract: A multi-band high-frequency circuit for performing wireless communications among pluralities of communication systems having different communication frequencies, comprising a high-frequency switch circuit comprising switching elements for switching the connection of pluralities of multi-band antennas to transmitting circuits and receiving circuits; a first diplexer circuit disposed between the high-frequency switch circuit and transmitting circuits for branching a high-frequency signal into frequency bands of the communication systems; a second diplexer circuit disposed between the high-frequency switch circuit and receiving circuits for branching a high-frequency signal into frequency bands of the communication systems; the first and second diplexer circuits each comprising a lower-frequency filter circuit and a higher-frequency filter circuit, a bandpass filter circuit being used as the lower-frequency filter circuit in the second diplexer circuit, or disposed between the lower-frequency filter circuit in the second diplexer circuit and the receiving circuit, the high-frequency switch circuit comprising first to fourth ports, the first port being connected to a first multi-band antenna, the second port being connected to a second multi-band antenna, the third port being connected to the first diplexer circuit, and the fourth port being connected to the second diplexer circuit; and the switching elements being controlled in an ON or OFF state to select a multi-band antenna for performing wireless communications and to switch the connection of the selected multi-band antenna to the transmitting circuit or the receiving circuit.

Parallel operation of passive power filter and hybrid power filter for harmonic suppression

Abstract: Harmonic pollution has been serious in recent years. Passive filters have been used to suppress harmonic current conventionally. However, passive power filters have the problem of resonance. To solve the resonance problem, active power filters and hybrid power filters were developed. After considering the power capacity and cost, the hybrid power filter is the better choice for the future. Many passive power filters have already been installed in the industry power systems. However, the elements of these passive power filters are often destroyed due to the resonance or the harmonic current injection of a neighbouring harmonic source. To improve the performance of passive power filters, a small capacity of hybrid power filter is proposed to connect in parallel with the existing passive power filters. The combined power filter system, which contains the parallel operation of existing passive power filters and hybrid power filters, is analysed and simulated. The simulation results show that the filter performance and resonance problem of existing passive power filters can be improved by applying the hybrid power filter.

A Hybrid Filter for the Suppression of Common-Mode Voltage and Differential-Mode Harmonics in Three-Phase Inverters With CPPM

Abstract: In the motor systems driven by sinusoidal pulse width modulation (SPWM) three-phase inverters, the peaks of common-mode (CM) voltage are so high that it will cause many negative effects. In this paper, a hybrid filter is presented to reduce the CM voltage (CMV) and the differential-mode (DM) harmonics in a three-phase inverter with carrier peak position modulation (CPPM). Because the use of CPPM strategy in the inverter can ensure that the output CMV will be only two levels in any condition, the simple active CM filter (composed of a half-bridge circuit) in the hybrid filter can effectively suppress the output CMV and CM current. The passive filter in the hybrid filter consists of an added single tuned filter and the original DM low-pass filter. The single tuned filter is designed to lower the DM harmonics, which are aggravated by the CPPM strategy in the carrier frequency band. Through the experiments, the validity of CMV and DM harmonics suppression by the hybrid filter in the three-phase inverter is verified and the calculation-control active CM filter is proved to be the best in the optional schemes.