Analysis of a Resonant Converter Controlled by Triac
Analytical and experimental considerations in the constant voltage transformer are presented. The constant voltage transformer consists of a linear reactor, a linear transformer, a capacitor, a triac, and a feedback circuit. The feedback circuit is used to make the triac fire precisely at any angle from zero to ¿/2 so as to keep output voltage constant. An analysis of this circuit is presented in which the higher harmonic currents generated in the triac are neglected and the output voltage is assumed to be kept constant. The experimental results agree well with the theoretical value with respect to the load characteristic, the voltage characteristic, the power factor, and the jumping phenomenon.
An analytic and computer study of the jump phenomenon in ferroresonant regulators
At certain ac input levels, discontinuous jumps appear in the ferroresonant regulator's steady-state output-versus-input characteristic. The conditions are derived under which this action, known as jump resonance, can occur. The describing function method of nonlinear system analysis is used to derive the range of circuit parameters in which the jump can occur. It is found that the conditions for the jump can be expressed in terms of the values of the linear energy storage elements and the character of the non-linearity, and that there exists a unit circle in the Nyquist plane which must be avoided to assure the nonoccurrence of the jump. The theoretical analysis is supplemented with a computer study of the circuit using an analog computer simulation program.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.