A.o. Smith Corporation

Yaskawa America, Inc.

Thor Technology Corporation

Joseph R Pottebaum

William Charles Phillips, Iii

Jerome J Reichard

Karl M Hink

John G Reichard

Brian W Geoffrey

John Alan Cairo

Theodore O Wiesendanger

Bruce C Wagner

Douglas B Weber

A variable frequency motor drive comprises a converter including a rectifier having an input for connection to an AC power source and converting the AC power to DC power. A DC bus is connected to the rectifier circuit. At least one bus capacitor is across the DC bus. An inverter receives DC power from the DC bus and converts the DC power to AC power to drive a motor. A controller is operatively connected to the converter. The controller comprises a speed control controlling the inverter responsive to a speed command to maintain a desired motor speed. A speed foldback control measures DC bus ripple voltage and regulates the speed command responsive to the measured DC bus ripple voltage.

Motor speed control with speed foldback for phase imbalance protection

An AC power line current regeneration method and circuitry energizes an AC power line from a DC power source through pulse width modulated switch means. The method and circuitry involves sampling the required peak line regeneration current value from a previous PWM cycle, I(peak last), sampling line regeneration current value at turn-on of the switch means, I(turn-on), and calculating the required peak line regeneration current value for the present PWM cycle, I(peak present), from both I(peak last) and I(turn-on).

AC power line current regeneration

A flame powered logic supply circuit (60) responds to a pilot flame (39b) and supplies electrical energy to power electronic logic circuitry (62) for a heater, such as a hot water heater (1), a furnace, or the like. A thermoelectric element (64) responds to the flame and outputs electrical current which is stored in an inductor (70). A pair of parallel circuit branches (78 and 80) are connected to the thermoelectric element (64) and the inductor (70). The first branch (78) has a semiconductor switch (82) with an on state during which current flow supplies energy to the inductor (70) which is stored therein. The second circuit branch (80) has a second energy storage component provided by a battery (90) which receives the stored energy from the inductor (70) during an off state of the semiconductor switch (82) to charge the battery (90) and maintain a given power rating thereof for powering electronic logic circuitry (62) of the heater. Monitoring circuitry is provided by a current sensing resistor (74) and a comparator (96) controlling the semiconductor switch (82) between its on and off states. Circuits (60, 60a) may be provided for both the pilot flame (39b) and a main burner flame (10a), or only for one or the other. The circuits (60, 60a) include indicia (94, 94a) providing a display indicating that each respective flame is lit and that energy is being supplied therefrom for powering the logic circuitry (62).

Heater with flame powered logic supply circuit

A speed control circuit (50) for a single phase AC induction motor (12) includes a phase control circuit (10) for connecting a main winding (16) to an AC source (18) at a variable time delay phase angle during the half cycle of the AC source, and a boost circuit (52) including a motor speed sensor (54, 56) sensing motor speed and altering the delay interval phase angle in response thereto. The boost circuit shortens the delay interval in response to decreasing motor speed, and lengthens the delay interval in response to increasing motor speed, such that almost full voltage is applied during starting of the motor, which voltage is reduced as the motor begins running.

Wide range, self-starting single phase motor speed control

A variable speed eddy current electric motor includes a zero-torque regulating circuit that senses and responds to the current flowing through an eddy current motor field coil. As the magnitude of the field coil's current is changed by the eddy current motor's speed control circuit, the operating method of the zero-torque regulating circuit supplies varying amounts of current to flow through the field coil in a direction opposite to that of the current applied thereto by the speed control circuit. Thus, when the eddy current motor's speed control circuit no longer causes any current to flow through the field coil, the current supplied to the field coil by the zero-torque regulating circuit produces a magnetic filed that removes all torque from the eddy current motor's output shaft.

Growing community of inventors

Brookfield, WI, United States of America

Joseph R Pottebaum