The patent's inventor is Etter, Brett E. (
This patent was filed on
From the background information supplied by the inventors, news correspondents obtained the following quote: "The present invention relates in general to the field of electronics, and more specifically to a power control system and method with voltage-based monitoring for over current protection.
"Power control systems often utilize one or more power conversion stages to convert alternating current (AC) voltages to direct current (DC) voltages or perform DC-to-DC conversions. For example, power control systems often contain a power factor correction (PFC) stage to provide power factor correction and regulate a link voltage, an output stage to provide output power to a load, and an isolation stage to isolate the PFC stage from the output stage.
"The PFC stage and the output stage of a power control system have a one hundred percent (100%) rated power and a maximum power. The rated power refers to power available from the power control system under nominal operation conditions. The maximum power refers to a percentage of the rated power that can be supplied by the power control system for at least a limited period of time while maintaining a regulated output voltage and without damaging the power control systems and/or the load. Once the load begins demanding more power than the maximum power of the power control system, an output current of the output stage will increase, and an output voltage of the output stage will decrease. A controller that controls the power control system monitors the output current. When the output current exceeds a predetermined threshold, the controller will enter an over-current protection mode. However, circuitry used to sense the current can cause overall power losses and, thus, lower the efficiency of the power control system.
"FIG. 1 depicts a power control system 100, and power control system 100 includes a PFC stage 102, an output stage 104, and an isolation stage 106 to isolate the PFC stage 102 from the output stage 104. Voltage source 108 supplies an alternating current (AC) input voltage V.sub.IN to a full bridge diode rectifier 110. Capacitor 112 provides high frequency filtering. The voltage source 108 is, for example, a public utility, and the AC voltage V.sub.IN is, for example, a 60 Hz/110 V line voltage in
"The power control system 100 includes a controller 114 to regulate a link voltage V.sub.LINK of PFC stage 102 and control isolation stage 106. Controller 114 generates a pulse-width modulated control signal CS.sub.0 to control power factor correction and regulate the link voltage V.sub.LINK of PFC stage 102. In one embodiment, PFC stage 102 is a boost-type, switching power converter, and control signal CS.sub.0 is a switch control signal that controls conversion of input voltage V.sub.X to link voltage V.sub.LINK. Controller 114 monitors voltages V.sub.X and V.sub.LINK to generate switch control signal CS.sub.0.
"Isolation stage 106 isolates the PFC stage 102 from the output stage 104. Depending upon the type of PFC stage 102, the link voltage V.sub.LINK is either a multiple or a fraction of the input voltage V.sub.X. In either situation, the load 116 may not be compatible with the value of the link voltage V.sub.LINK or compatible with a DC voltage in general. Isolation stage 106 includes a transformer 118 to convert the link voltage V.sub.LINK into the output voltage V.sub.OUT. Transformer 118 is a flyback type transformer that includes switch 124. Control signal CS.sub.F controls the conductivity of switch 124 to convert link voltage V.sub.LINK into a time-varying, primary-side voltage V.sub.P to allow the primary-side windings 120 of transformer 118 to alternately store energy and then transfer energy to the secondary-side windings 122. In one embodiment, switch 124 is a field effect transistor (FET). Transformer 118 converts the primary side voltage V.sub.P into a secondary voltage V.sub.S. A variety of other topologies are well-known for isolation stage 106, such as half-bridge and full-bridge topologies as discussed in chapter 6 of Fundamentals of Power Electronics--Second Edition by Erickson and Maksimovi , publisher
"The output stage 104 converts the secondary voltage V.sub.S into the output voltage V.sub.OUT. The topology of output stage 104 is a matter of design choice. Exemplary topologies are a half-bridge buck converter and a full-bridge buck converter. Examples of output stage 104 are also discussed in chapter 6 of Fundamentals of
"Power control system 100 supplies load 116 with output voltage V.sub.OUT and output current i.sub.OUT. The load 116 is any device that can utilize the power provided by output stage 104. Controller 114 regulates the link voltage V.sub.LINK and the primary-side voltage V.sub.P to establish a particular value for the secondary-side load current i.sub.OUT. Controller 114 regulates the primary-side voltage V.sub.P by controlling the duty cycles of control signal CS.sub.F. Controller 114 obtains a value of the output current i.sub.OUT by sensing a feedback voltage V.sub.R.sub.--.sub.SENSE across sense resistor 126. The output current i.sub.OUT equals V.sub.R.sub.--.sub.SENSE/R, and R is the known resistance of sense resistor 126. Controller 114 regulates link voltage V.sub.LINK and the primary-side V.sub.P based on the value of output current i.sub.OUT. If the value of the output current i.sub.OUT is too large, controller 114 decreases the duty cycle of control signal CS.sub.F to reduce the value of output current i.sub.OUT. If the value of secondary side current i.sub.OUT is too small, controller 114 increases the duty cycle of control signal CS.sub.F to increase the value output current i.sub.OUT.
"PFC stage 102 has a rated power of P.sub.RATED and a maximum power of P.sub.MAX. If load 116 demands more power than the maximum power P.sub.MAX, the output current i.sub.OUT increases and the output voltage V.sub.OUT decreases. If the output current i.sub.OUT exceeds a predetermined threshold value, the power control system 100 enters an over current protection mode. The particular over current protection mode involves, for example, turning the power control system 100 OFF to protect components of the power control system 100 from damage.
"Power efficiency is generally a concern when designing and utilizing power control system 100. However, the voltage drop corresponding to the feedback voltage V.sub.R.sub.--.sub.SENSE across sense resistor 126 represents a power loss. Such power loss is disadvantageous."
Supplementing the background information on this patent, VerticalNews reporters also obtained the inventor's summary information for this patent: "In one embodiment of the present invention, an apparatus includes a controller to control a power supply and provide over current protection. The controller is configured to provide over current protection for the power supply using power utilization information and an output voltage of an output stage of the power supply. The power utilization information represents power utilization of the power supply.
"In another embodiment of the present invention, a method includes controlling a power supply. Controlling the power supply includes using power utilization information and an output voltage of an output stage of the power supply to provide over current protection for the power supply. The power utilization information represents power utilization of the power supply.
"In a further embodiment of the invention, an apparatus includes a controller to control a switching power supply and provide over current protection. The controller is configured to monitor a link voltage of the switching power converter and to determine a power utilization factor. The controller is further configured to monitor an output voltage of the switching power converter and to determine if the power utilization factor is greater than a power utilization factor threshold value. The controller is further configured to determine if an output voltage of the switching power converter is greater than an output voltage threshold value. If the power utilization factor is greater than a power utilization factor threshold value and the output voltage is less than the output voltage threshold value, then enter an over current protection mode. The power utilization factor represents power utilization of the power supply."
For the URL and additional information on this patent, see: Etter, Brett E.. Power System Having Voltage-Based Monitoring for over Current Protection. U.S. Patent Number 8654483, filed
Keywords for this news article include: Electronics,
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