This paper is aimed at the sensrorless control of CAPACITOR in single phase induction motors. This is done towards three objectives i.e. maximization of average torque, minimization of torque pulsations and optimization of torque. The objectives are achieved by first obtaining the average torque and pulsation torque in terms of a variable capacitance and motor speed. The objective functions are then defined mathematically. Later the appropriate capacitance is calculated in a wide range of motor speed according to each objective. The motor speed is estimated by three methods using electrical SENSORs. The estimated speed is used for the switching of a power electronic switch in parallel with a constant CAPACITOR to provide an appropriate capacitance in each case. Extensive simulation results are presented to verify the effectiveness of the SENSORless CAPACITOR switching in achieving the torque control objectives.

Design and construction of a CAPACITOR SENSOR with a precise readout system are described in this paper. A variable air-gap capacitive transducer was constructed and for signal measurement a successful attempt was made to exploit the capacitance changes in terms of the phase angle of the detected signal. The reported setup makes it possible to detect capacitance changes of the order of 2.5 fF in a 4.5 pF range and the readout circuit can detect a capacitance change of about 22 aF (5 in 106). There is a linear relation between the air-gap distance and the output of the SENSOR over an experimented gap range of 0.5 - 4.5 mm. It shows a nonlinearity deviation factor of 1% from the expected theoretical line. The dynamic range of the system is variable from 5 mm to 2.5mm and it mainly depends on the initial air-gap distance. Adding a stray capacitance of 180 pF to the system only causes a 0.1% error in the SENSOR output. In comparison with the other SENSOR systems the one reported in this paper is much more sensitive, reliable, and stray-immune to electrical interferences.

In this article, the authors explain their experience in designing and building a heat CAPACITOR wall by making use of indissoluble and permanent garbage, e.g. plastic bottles. The result is a more-or-Iess light weight wall made of bottles filled with water. The bottles are sandwiched between two layers of translucent polycarbonate sheets as the external surface, and an opaque fireproof layer? s the internal one. A thick cotton screen with a reflective face is used to prevent heat loss during cold and heat gain during warm seasons. The wall is structurally self-supporting and is very effective as heat and sound isolator.

For synchronization with the grid and controlling the injected active and reactive currents of the LCL-filter based grid-tied inverters, CAPACITOR voltages can be sampled. An LCL filter attenuates the switching harmonics effectively but needs an extra SENSOR for the LCL filter resonance damping. Popular methods use CAPACITOR currents for the LCL filter resonance damping. Theoretically, the derivative of CAPACITOR voltage, which is proportional to the CAPACITOR current, damps the resonance, and the extra SENSOR is avoided. However, traditional discretization methods for digital implementation of the derivative operator are not valid when the resonance frequency is high. Indeed, they don't preserve the phase and magnitude of the ’s’ function in the resonance frequency region. This paper introduces an effective method for discretizing the ’s’ function in the desired frequency range. The CAPACITOR voltages of the LCL filter are sampled and the proposed function makes their derivative. The output of the derivative function with a tuned gain is added to the controller’s output for damping the LCL filter resonance. The simulation results show the effectiveness of the proposed method.