CogniPower Patents Summary Technical Description

1. Patent 7642758, filed 11/6/2006 in the Patent and Trademark Office in Washington, D.C.; issued 1/5/2010. International patent applications have been filed in Canada, the European Union, Japan and Korea. Power Conversion Regulator with Predictive Energy Balancing.

The first patent application covers predictive energy balancing for switched mode power converter (SMPC) control. The principle of energy prediction is covered in the broadest possible terms in the allowed claims. In essence, the inductor is energized until it holds enough energy to balance the energy deficit at the load. The regulation decision, made during an individual control cycle, is based on the predicted state at the end of that control cycle. In so doing, the filter pole created by the output filter capacitor is effectively removed from the feedback loop. That removes the tendency toward oscillation shown by conventional controls, and eliminates the need to compromise between stability and responsiveness. Controllers according to this invention can be built as analog or digital circuitry. The main advantage enabled by prediction is intrinsic stability, which leads to superior agility, flexibility, transient response, efficiency, and reliability. The broadest claims were allowed in the first issued patent. We refiled for the disallowed claims and they issued in their entirety as patent 7965064 on June 21, 2011.

2. Patent 7492221, filed 11/6/2006 in the Patent and Trademark Office, Washington, D.C.; issued 2/17/2009. Power Conversion Regulator with Exponentiating Feedback Loop

This patent covers analogous improvements in analog circuits. It applies to analog power regulators and to amplifiers, in general. These devices can be made faster and more stable without increasing their cost by using exponential feedback. Shaping feedback to match the energy equations instead of according to linear voltage differences allows faster settling at a given gain. Using this technique, amplifier compensation becomes a much easier task. In addition to three-terminal regulators, power amplifiers, buffers and drivers can be improved using this technique. The principle is general and the claims are broad.

3. Patent 7786709, filed 3/5/07 in the Patent and Trademark Office in Washington, D.C.; issued 8/31/10. Bi-polar Bi-directional Energy Balancing Power Conversion Engine

The third patent includes a number of related inventions. It was split by the Patent Office into five patents. The broadest 15 claims are included in the issued patent. The four split patents remain pending. This group of patents covers means to build and control bi-directional, bipolar SMPCs. These define a new product category. Also covered here are several novel topologies for better SMPCs, and novel control strategies, some not requiring prediction. This work was done in anticipation of possible future attempts to circumvent the advantages protected in the first CogniPower patent. Other claims in this patent cover improved SMPC circuit protection methods, improved ways to control SMPCs that cross from discontinuous to continuous mode, adaptive control techniques that increase efficiency, and means for using recirculation in a switched inductor to aid regulation. Some of these novel converters can recover reactive energy from the load in order to achieve even greater efficiency.

4. Patent 8004344, filed 12/15/08 in the Patent and Trademark Office in Washington, D.C.; issued 8/23/2011. Gate Charge Retaining Switch

The fourth patent covers improved controls for the switches used in SMPCs. Faster, more precise control of switches is possible using the novel technique covered here. The bistable nature of a FET or IGBT is used to aid in faster switching with more precise timing. The gate of a power switch can be allowed to float for a brief period before being switched to the other state. Taking advantage of that bistability during the crucial periods enables lower latency and faster switch transitions, enabling higher efficiency. These improved switch controls can be used to advantage in any power switching application. We have built and tested five generations of these devices. The most basic claims were found to have been anticipated in the prior art, but claims covering important details required for implementation were granted.

5. Patent 8134347, filed 1/24/2008 in the Patent and Trademark Office in Washington, D.C.; issued 3/13/2012. Apparatus and Method for Recycling the Energy from Load Capacitance

The fifth patent application covers the basic principle of recovering reactive energy from a load when cycling power. Its main application is seen to be computer power supplies, though the technique could eventually migrate to almost any power converter. The basis for energy savings here is that circuitry need only be fully powered for the actual time that it is performing useful work. With capacitive energy recovery, circuitry can be turned off or powered at a minimum level for state preservation without unproductively dissipating the energy stored in filter and load capacitance.

Inrush currents are high during power-up because filter and load capacitance needs to be charged, and a significant amount of energy is required. The normal way to deal with inrush currents is to slowly ramp voltage at power-up. That requirement limits the possibilities for saving energy by powering-up on demand, and powering-down during idle periods. Instead, a POL converter with local storage can supply energy at power-up to charge filter and load capacitance quickly from its local storage reservoir. At power-down, such a POL converter can draw that filter and load capacitive energy back into local storage. Circuitry that is now left ON constantly, but is only sometimes used, could be efficiently powered up and down as needed. Substantial amounts of power can be saved in the process. At the cost of the ability to handle higher peak currents, much lower average power can be achieved. The small additional POL cost can be mitigated by reducing the size of heat sinks and fans. We have responded to the examiner's first action.

6. Patent Application 61042106, filed 4/3/08 in the Patent and Trademark Office in Washington, D.C.; publication date 10/08/2009 DC Common Mode Level Shifter

The sixth patent application covers CogniPower's improved method of monitoring current in SMPCs.

The technique allows fast and accurate measurement of current even in the difficult electrical environment found inside SMPCs. The same principle can be applied to amplifiers, particularly those that must tolerate extreme voltages. Other applications include high-energy physics, power generation and smart grid monitoring. CogniPower's CP10 Current Probe is based on this patent. The underlying principle is to use a commutated common mode choke to level-shift a small differential signal in the presence of large, fast-slewing common mode voltages. The special value of this method is that its common mode rejection increases with common mode frequency, while conventional differential amplifiers rapidly loose CMR at higher frequencies.

The use of a common mode choke as a level shifter has many unexplored applications. One application that we have explored is for driving high-side switches. Patent 8, below, covers that particular case. This patent application has not yet been examined.

7. Patent Application 12/949,345, filed 11/18/10 in the Patent and Trademark Office in Washington, D.C.; ENERGY PREDICTIVE BUCK CONVERTER;

This application covers simple ways to add predictive energy balancing control to conventional buck converters. These controllers can be based on volt-time product, eliminating the need for fast and accurate current sensing. Predictive controls can recover more smoothly from disruptions and can avoid the tendency toward destructive runaway. This patent has been allowed, and is in the process of issuing.

8. Patent Application 12/952,893, filed 11/23/10 in the Patent and Trademark Office in Washington, D.C.; SWITCH WITH COMMON MODE CHOKE; publication date, May 26, 2011

This application combines Patents 4 and 6 to make a new class of switch driver. This method of driving a FET or IGBT switch allows superior timing, in particular, for the high side switch in a totem pole. It is faster and more precise than prior art methods. Dead time can be held to a few nS without the need for closed-loop adaptive dead time control. CogniPower's APEC 2010 Presentation describes this method in detail.

9. Patent Application 13/015,891, filed 1/28/11 in the Patent and Trademark Office in Washington, D.C.; UNIVERSAL SINGLE-STAGE POWER CONVERTER WITH PFC CAPABILITY; publication date, August 4, 2011

This patent application shows how extensions of the first and third patents can be used to move power efficiently between multiple ports by making choices on a cycle by cycle basis. The minimum topology requires six switches and includes an input port, an output port and a storage port. Because the current in a switched inductor cannot change instantaneously, to be completely opportunistic, a power converter must be able to perform any energy transfer with any magnitude and polarity of switched inductor current flowing at the start of a chopping cycle. The addition of a few extra switches enables complete flexibility. Once such a set of rules is in place, energy need only move from the best source to the best destination during any given cycle, with no limitations imposed by previous behavior or past assumptions.

Another benefit of such a structure and set of controls is that multiple control loops can be closed through the same switched inductor using time multiplexing. In the power factor correction (PFC) case, the input current is regulated independently of the output voltage. A slower, non-critical loop controls the average energy moved into or out of storage. One cycle's worth of energy for storage capacity is sufficient for PFC applications. By incorporating larger storage capacity, UPS functionality is achieved.

A conventional AC to DC system would include a bridge rectifier, a boost PFC converter, a buck converter, and an additional switching stage to incorporate the storage. All of the above can be replaced with a single stage converter according to this invention, using only one switched inductor, and fewer switching elements than the usual combination of conventional stages. Since the inefficiencies of series-connected power stages multiply, employing only a single power conversion stage provides substantial efficiency gains.

10. Patent Application, filed 11/14/11 COMPOUND POWER CONVERTER for EFFICIENT POWER FACTOR CORRECTION; publication date, May 23, 2013

A new topology for PFC switched mode power converter applications that conventionally use two stages of power conversion in series. The compound converter moves power through only one stage of power conversion where possible, and uses a second supplemental power conversion stage when necessary and/or desirable. This topology offers advantages for regulation, efficiency, flexibility and simplicity. It lends itself to more efficient Power Factor Correction, to uninterruptible power supply applications, and to applications requiring redundancy for reliability. This topology adapts to multi-output supplies, bipolar supplies, to AC-AC conversion and to power amplifiers. Applications include laptop-style AC-DC converters and bus converters. While disruptive in some ways, this patent is directed at drop-in replacement power supplies for AC-to-DC conversion.

11. Patent Application, filed 12/29/11 SINGLE-TRANSFORMER FULL-DUPLEX DIGITAL ISOLATOR; issued July 23, 2013

A new method for sending bidirectional digital information through a single transformer isolator is described. This technique was developed for IGBT switch drivers where status information must be sent back across an isolation barrier from the IGBT to the controller. Existing products can send information in both directions, but not at the same time. The conventional method requires "collision avoidance" logic and forces blind periods when information can not be transmitted. This new method allows data to pass simultaneously in opposite directions through the same transformer. Commercial digital isolators for the purpose use two transformers, one for each direction of data flow. By eliminating one transformer, coupling capacitance across the isolation barrier is minimized. Size and cost also benefit.

12. Patent Application, filed 7/3/12 POWER CONVERTER with TRANSFORMER FEEDBACK ISOLATION (unpublished)

A new form of AC-DC converter control suited for wall adapters or battery chargers is adapted for low cost, small size, and better efficiency, particularly at low loads. Improved feedback for regulation does not require an optocoupler. Filter capacitors can be much smaller than those needed in conventional converters, allowing the use of ceramic capacitors instead of bulky electrolytic capacitors or expensive tantalum capacitors. Unloaded power consumption has been reduced to just a few milliwatts.

13. Patent Application, filed 1/14/13 FLYBACK AMPLIFIER with DIRECT FEEDBACK (unpublished)

Bidirectional Predictive Energy Balancing Flyback Converters suited for power amplifiers and audio amplifiers are described here. These are Predictive Energy Balancing power converters reduced to their simplest form. Topologies that have been of little value in the past become capable when equipped with agile controls. One particular target application is a cell phone audio amplifier for piezo speakers. AC motor drive is another application.

The intellectual property described here is owned by CogniPower, LLC.

CogniPower, LLC
3217 Phoenixville Pike
Malvern, PA 19355