A current inrush limiting technique for a switching power converter. In one aspect, a switching power converter includes a main power switch and a current sensor. When the input current exceeds a first threshold, the main power switch is opened. When the input current exceeds a second threshold, higher than the first threshold, a current-limiting resistance is coupled to receive the input current. Accordingly, the input current is limited in two stages by two different techniques. In another aspect, a bleed resistor receives current from a power source for providing power to a controller for the power converter. After start-up, such as when an output voltage of the power converter is available to provide power to the controller, the current-limiting resistor is shorted and the bleed resistor is effectively removed. A single pin of an integrated circuit controller controls shorting of the current-limiting resistor and removal of the bleed resistor.

Current inrush limiting and bleed resistor current inhibiting in a switching power converter

An improved technique for limiting current in a switching power converter. The switching power converter includes a soft-start circuit which slowly increases a switching duty cycle upon power-up. Once the converter is operating normally, the duty cycle is controlled to regulate the output voltage. In the event an excessive output current is detected, soft-start circuit is controlled to reduce the switching duty cycle. More particularly, a soft-start capacitor may be discharged during portions of a clock period used to control switching.

Current limiting technique for a switching power converter

A power supply circuit comprising a first switching transistor having a control terminal and a control terminal switching threshold and that charges current from a voltage source into a charge storage capacitor, a control circuit controlling the on/off operation of the switching transistor whereby the switching transistor is turned on when the voltage of the voltage source is below a predetermined level and turned off when the voltage of the voltage source is above the predetermined level, a control voltage supply circuit providing a control voltage to the control terminal of the switching transistor substantially in excess of the switching threshold when the voltage of the voltage source is below the predetermined voltage thereby to drive the switching transistor on in a saturated region of operation; and a charge storage capacitor for providing an output voltage of the power supply.

High efficiency off-line linear power supply

A system and method are provided for reducing the energy consumed by a pump jack electric motor by reducing the supply voltage to the motor when the motor would be generating energy in open loop mode. By substantially eliminating the energy generation mode, the braking action of the utility grid in limiting the acceleration of the motor and system that would otherwise occur is substantially removed. The motor and system will speed up, allowing the natural kinetic energy of the cyclic motion to perform part of the pumping action. A closed loop controller in electrical connection with the motor computes the necessary information from the observed phase angle between the voltage and current supplied to the motor. By reducing the supply voltage to the motor, the observed phase angle may be reduced to a target phase angle value. By allowing some current flow, primarily of a reactive nature, an observable feedback parameter may be used in the closed loop control system as an indication of the load condition, to which the closed loop motor controller may react, supplying power when needed, such as in the energy consumption mode. The electric motor may be effectively turned off, but without completely cutting the power to the motor. During both the energy consumption mode and the period that open loop energy generation would be occurring, the closed loop motor controller may reduce the observed phase angle to a target phase angle by reducing the supply voltage. Any further reduction in the observed phase angle below the target phase angle may be interpreted as an increase in motor load, to which the motor controller may respond by increasing the supply voltage to the motor until the target phase angle is once again reached.

Energy saving system and method for devices with rotating or reciprocating masses

Current sensing resistors are connected directly to output terminals of MOSFETs forming the series switching stage of a PWM sinewave dimmer. An analog sensed current signal is coupled through an EMI resistant current link to comparators that provide an overcurrent indication in response to an overcurrent condition. A logic circuit overrides PWM control signals from a programmable controller, and operates drivers to render the series switching stage nonconductive and to render a clamp switching stage conductive until after the end of the current PWM duty cycle power on segment. The logic circuit sends an overcurrent signal through an optocoupler to an input of the programmable controller. The input of the controller is polled at a clock frequency for overcurrent signals and if the count exceeds a limit in any half cycle, or a maximum sum in sixteen half cycles of the AC supply, the series switching stage is rendered nonconductive and the clamp switching stage is rendered conductive pending a reset signal.

Overcurrent protection for solid state switching system

The present invention relates to apparatus used in power control, such as apparatus for controlling the power level in an AC electrical circuit. Such an apparatus is referred to as an AC power converter. In one form, the present invention particularly relates to a power converter suitable for use in lighting dimmer control although other applications of the present invention are not to be excluded from the scope of the present application. A number of aspects of the power converter are disclosed. One aspect is directed to the problem of freewheeling in a power converter. In another aspect the linearity of the circuit transfer characteristic is improved when operating in response to small load outputs. A further aspect relates to surge detection by controlling the pulse width and accordingly, the amplitude of a spike. In a still further aspect, communication between a number of power converters uses a network such as ethernet, or preferably LONTM.

Qunying Yao

Papers

Ac power converter