Francis T. Thompson

A Dynamic Model of a Drum-Type Boiler System

A dynamic model of a drum-type electric utility boiler, which is suitable for use in designing and evaluating a multivariable controller, is described. State-space matrix equations are used in making the model. Unique iterative methods are developed for obtaining accurate steady-state profiles of the superheater and waterwall sections. Constants for the dynamic model are derived using these profiles. An original superheater model provides the transient response of steam temperature, pressure, enthalpy, and mass flow rate.

Advanced electronic control systems for electric vehicles

The characteristics and relative advantages of several types of electric vehicle control systems are discussed. An advanced electronic control system for a separately excited dc motor is described. Performance characteristics of an electric vehicle using this control are discussed and recommendations for future systems are given.

Throttle Valve Position Control System

A high-accuracy steam valve controller which uses a dc motor and gear train to position a steam valve shaft is described. The system responds to an error signal derived from the difference between an input reference and an output feedback signal. The error signal is amplified to control two firing pulse generators. The firing pulse generators drive a set of eight SCRs in a dual bridge configuration, providing bidirectional armature drive for a 1/6-hp 115-volt dc motor. The system could easily be modified to handle larger motors by using larger devices in the dual bridge power circuit.

Speed, Acceleration, and Load Control Solid-State System

An all solid-state system for controlling the acceleration, speed, and load of central station steam turbines or the acceleration and speed of paper machine drive turbines is described. This new high-performance system eliminates the moving parts and gives lower drift and better reliability than previous solutions which used a motor driven potentiometer or an integrator operational amplifier. A desired speed is preset in a digital register and the speed of the turbine is brought toward this desired value at a selected rate. A control is provided to hold any present operating speed indefinitely. For central station steam turbines, the same equipment is used for load control after synchronization. Since high precision is required, the system is digital and drives a simple digital to analog converter to provide the analog output signal. The equipment may be operated from a remote panel or by a digital computer.