Abstract: An HVAC system has at least one variable speed controller for an AC induction motor, especially of the Permanent Split Capacitor (PSC) type. The variable speed controller provides switched power via a modulating triac to the main coils of the motor and constant power via an on/off triac to the auxiliary coils during operation. A large value capacitor is placed in line with the auxiliary coils to reduce power consumption and current draw over that of known systems. Power to the motor can be turned off to provide for motor speed sensing through monitoring the frequency of a generated voltage when the power is turned off. Frequency-based motor speed sensing is accomplished by shutting off all current to the motor and measuring zero crossings on the generated voltage of the decaying magnetic field. The controller can be easily retrofitted onto existing motors. An optional controller bypass is provided to run the motor at rated speed in case of controller failure.

Abstract: An HVAC system has at least one variable speed controller for an AC induction motor, especially of the Permanent Split Capacitor (PSC) type. The variable speed controller provides switched power via a modulating triac to the main coils of the motor and constant power via an on/off triac to the auxiliary coils during operation. A large value capacitor is placed in line with the auxiliary coils to reduce power consumption and current draw over that of known systems. Power to the motor can be turned off to provide for motor speed sensing through monitoring the frequency of a generated voltage when the power is turned off. Frequency-based motor speed sensing is accomplished by shutting off all current to the motor and measuring zero crossings on the generated voltage of the decaying magnetic field. The controller can be easily retrofitted onto existing motors. An optional controller bypass is provided to run the motor at rated speed in case of controller failure.

Abstract: A commercial application for a four-step switching PWM single phase AC controller for a load such as an induction motor or the like has a digital microcontroller for PWM signal generation and enhanced MOSFET switching control, and provides a multiplicity of discrete speed settings to make any single phase AC driven device easily and cheaply converted to efficient variable speed operation. Only two MOSFET gate drive optocouplers are provided on the high side of line voltage for reduced cost. Series transistors are programed to be left full on at maximum motor speed for increased efficiency. Current limit and under voltage sensing for fault protection are provided.

Abstract: An electric motor and its controller are specially adapted for variable speed applications. The stator of the motor has its main windings controlled by triacs. The triacs are placed to allow the main windings to operate in series at low speed and in parallel at high speeds. The firing delay of the operating triacs is controlled in both series and parallel winding operations to aid in smooth operation of the motor. The auxiliary winding is preferably left uncontrolled to contribute a regular sinusoidal component to the windings power at all times. The controller receives the speed command and figures firing delay and outputs triac control pulses at one of a plurality of settings to bring the motor to the selected speed. In this manner a simple, inexpensive, and continuously variable speed motor may be realized with good performance characteristics.

Abstract: In some embodiments, a light bulb for an electrodeless discharge lamp has a protuberance such that the cold spot of the bulb is located in the protuberance. The protuberance is spaced from the induction coil of the lamp so as to be easily accessible. Hence the cold spot temperature is easy to measure and control. In some embodiments, heat sinks are provided to cool the light bulb. An active control element including a Peltier element is provided to control the cold spot temperature.

Abstract: In some embodiments, a light bulb for an electrodeless discharge lamp has a protuberance such that the cold spot of the bulb is located in the protuberance. The protuberance is spaced from the induction coil of the lamp so as to be easily accessible. Hence the cold spot temperature is easy to measure and control. In some embodiments, heat sinks are provided to cool the light bulb. An active control element including a Peltier element is provided to control the cold spot temperature.

Abstract: In some embodiments, a light bulb for an electrodeless discharge lamp has a protuberance such that the cold spot of the bulb is located in the protuberance. The protuberance is spaced from the induction coil of the lamp so as to be easily accessible. Hence the cold spot temperature is easy to measure and control. In some embodiments, heat sinks are provided to cool the light bulb. An active control element including a Peltier element is provided to control the cold spot temperature.

Abstract: An arrangement for adjusting the intensity of an electrodeless discharge lamp is described. In one embodiment the high-frequency signal delivered to the induction coil is interrupted during a predetermined portion of a full duty cycle. This function is provided by a dimmer control unit which may be in an analog or digital form and may respond to a control signal provided by a potentiometer, a three-way lighting fixture or an addressable, remote controlled interface with data transmitted over the power lines or over a radio or infrared communication channel. In another embodiment the dimmer control unit alters the amplitude of the high-frequency signal supplied to the lamp's induction coil.

Abstract: A cost-efficient electrically conductive screen and shield for substantially shielding radio frequency electromagnetic radiation emitted beyond the discharge vessel and the electronic circuitry of an electrodeless discharge lamp is disclosed. The conductive screen and/or shield is disposed outside the space occupied by the gaseous mixture and is grounded to the power supply. This shielding reduces the emission of electromagnetic radiation and, in particular, enables the discharge lamp to comply with FCC standards imposed with respect to the maximum admissible level of interference with wireless communication equipment such as radios and televisions.