Abstract: Control circuitry controls a boost regulator during a start-up period. The control circuitry may comprise an oscillator for generating a clock signal. The oscillator may be configured for ramping up a frequency of the clock signal in accordance with an voltage to be applied to the oscillator and varied during the start-up period. The control circuit may further include a switching circuit configured for controlling a power switch of the boost regulator in response to the clock signal from the oscillator. The switching circuit can control the power switch to have an on-time which is largely independent of the operating frequency of the oscillator. The voltage to be applied to the oscillator may have the same initial voltage level upon startup of the control circuit, independent of an output voltage of the boost regulator.

Abstract: A fusion joining apparatus includes an electrical power source, a first frequency converter coupled to the electrical power source, a connector for connection to an induction fusion heater, a second frequency converter and a controller. During operation, the electrical power source generates source electrical power at a source voltage and a source frequency. The first frequency converter steps up the voltage and the frequency of the source electrical power to produce high voltage electrical power. The second frequency converter reduces the voltage and frequency of the high voltage electrical power and produces low voltage electrical power. The second frequency converter has terminals for connection to a resistance fusion heater to provide the low voltage electrical power to the resistance fusion heater.

Abstract: A method and apparatus for fusion joining polyethylene pipe. A power source supplies an input power to an input of a power supply. The input power has generally constant current and is converted to an output power at a relatively high frequency. The relatively high frequency output power is delivered to an installation tool. The output power delivered to the installation tool is controlled. The output power can be controlled as a function of ambient temperature surrounding the installation tool.