** ENERGY HARVESTING RESISTOR**

** 12/839,890
filed
9-10-10 at USPTO**

**Start off looking at a simplified DC to DC convertor,
which is using**

**a big transistor inverter to drive an inductor with a **

**50% duty cycle. The inductor L1, capacitor C1 and
resistor RL1**

**are acting like a low pass filter to produce an output
voltage**

**at Out1 which is 50% of the supply voltage Vcc1. The
two transistor**

**MP1 and MN1 are acting like switches. For the sake of **

**making calculations easier, the effective resistances
of MP1, MN1, **

**and L1 are being modeled at zero. **

**The inductor will be seeing a DC current of 500mA and
an AC**

**current of +/-60mA. Notice how the inverter is
multiplexing the**

**DC and AC components of the current. The AC component
averages out**

**to zero while the DC component gets 50% multiplexed.
The powers**

**are obeying the laws of thermal dynamics. Load
resistor RL1 is**

**dissipating 1.25W of heat, and Vcc1 is supplying it. **

**When the circuit of FIG 1 goes dual supply, having RL2
at ground**

**will mean no DC current flows, and again all the AC
currents average**

**out to zero for the multiplexing of the inverter
Invert_1. Since**

**all resistance except RL2 are modeled at zero, no
power is being**

**dissipated anywhere. **

**Now add an external common mode power power source
Vcm3 to**

**the circuit of FIG2. With Vcm3 connected to RL3 and
set to**

**-2.5V, then 500mA is flowing through RL3. The Out3 of
the **

**DC to DC converter is acting like a ground. It
supplies the**

**500mA to RL3, but grounds don't dissipate any power.
The **

**external Vcm3 sources is giving out 1.25W of power and
RL3**

**is receiving it all. **

**It turns out that the DC component of the 500mA is
being **

**multiplexed equally between Vcc3 and Vee3. Now pulling**

**250mA out of the positive terminal of a 2.5V volt
battery**

**is discharging it by 626mW. But pulling 250mA out of
the**

**negative node of a battery like Vee3 is actually
charging **

**the battery. Again modeling Vcc3 and Vee3 as being
like ideal**

**batteries, the discharge of Vcc3 is being counter by
the **

**charging up of Vee3. So the DC to DC converter output
is acting **

**like a ground. It has 500mA being pull out of it with **

**out dissipating any power. It is just transferring
power from**

**Vee3 to Vee3.**

**Now if RL3 where instead connected to Vee3, then both
Vee3 and**

**Vcc3 would be dissipating 625mW of power to add up a 5
volt**

**supply dissipating 1.25W, just like in FIG 1. **

**FIG 4 shows that the same is true when Vcm4 is changed
to +2.5V.**

**When the DC to DC converter is acting like a ground,
current**

**into it or out of it should not dissipate any power.
If Vcc4**

**and Vee4 are ideal supplies, then energy is simply
being transferred **

**rather than dissipated. **

**Now take the circuit of FIG 4, and change the duty
cycle of the output**

**to 75%. This will cause Out5 to go to 1.25V. So now
RL5 sees**

**1.25v across it just like Out5. And both RL5 and Out5
of the**

**DC to DC convertor are conducting 250mA of current. The**

**external voltage source Vcm5 is being discharged by **

**625mW. And half of that power is going into RL5. So
the DC to**

**DC convertor is acting like a 5 Ohm resistor in terms
of voltage,**

**current, and even the absorption of power. **

**Since the output duty cycle is 75%, most of the 250mA
current is**

**going into charging up Vcc5, and some is discharging
Vee5. Taking**

**the supplies together, there is a net charge up of
312.5mW of**

**power. So the power that the DC to DC convertor is
absorbing is**

**all being transferred to its supplies. **

**Change the polarity of Vcm6 and the output duty cycle
to 25% will**

**make the DC to DC converting in FIG 6 still look like
a 5 Ohm**

**resistor. And now Vee6 is getting charged up. **

**Making the output impedance of a DC to DC convertor
behave like**

**a 5 Ohm resistor simply involves monitoring the output
current**

**and adjusting the duty cycle accordingly. Now
the DC to**

**DC convertor will look like a nice linear resistor. It
still**

**obeys Ohms law and the laws of thermal dynamics. But
it does**

**so by transferring the energy is absorbs to its
supplies.**

**FIG 8 shows Vcm7 as a +/- 2.5V 50Hz AC source, and it
power loss will **

**be as what would be expected of a 5 Ohm load.
Monitoring the**

**net power of the two supplies shows that the AC power
is being**

**transferred to two DC power supplies without a
rectifier. **

**Now while this harvesting resistor can harvest either
AC or DC**

**power, an external DC power source could discharge
either**

**Vcc9 or Vee9. One way to solve this is to just go
single supply,**

**provided the input power will always be in one
direction. But an AC **

**resistor will need two supplies, and as was shown in
the circuits **

**of FIG 3 or FIG 4, FIG 9 shows
how it is not hard to
shift power**

**around between
two supplies. **

**Harvesting AC power to a DC level without a rectifier
is a**

**little unusual. FIG 10 shows the present art as just
peak**

**detecting off the AC waveform. But the fact that the
power**

**is be transferred as a linear resistor has some
interesting**

**applications. **

**Mechanical systems and electrical systems map very
well to **

**one another. An automobile suspension system is much
like a**

**critically damped LRC network. And a shock absorber,
which**

**can be modeled as a metal disk in a viscous fluid, is
serving**

**as the dampening resistor. **

**But a magnet moving in and out of a coil which has a
resistor**

**across it can perform the same function. If RL_12 is
small**

**enough, the voltage across Coil_12 which is induced by
Magnet_12**

**moving in and out will produce and opposing magnetic
force**

**to resist movement. So instead of dissipating energy
in a**

**viscous liquid as in Shock_Absorber_11, energy can be
dissipated**

**into RL_12 instead. So now a shock absorber function
could be**

**replaced by an energy harvesting method. This
potential application
has long been recognized. The following are some patents.
**

**1976792_ELECTRIC_SHOCK_ABSORBER**

**3941402_Electromagnetic_shock_absorber
4032829_Road_shock_energy_converter
5347186_Linear_motion_electric_power_generator
5818132_Linear_motion_electric_power_generator
6952060_Electromagnetic_linear_generator
**

**7357229_Electromagnetic_shock_absorber**

**7362003_Coil_switching_circuit_for_linear_generation**

**Some more information concerning the harvesting of shock absorber
energy.**

**electromagnetic
energy harvester for vehicle suspensions**

**Regenerative
Shock Absorber**

**Vehicle
shock absorber recovers energy**

**A common method of energy
harvesting ****involves the used of
vibration. When the energy is
periodic, methods such as what
is used for 60Hz AC are perhaps the most convenient.
**

**5578877_Apparatus_for_converting_vibratory_motion**

**6897573_Electrical_voltage_generating_device
**

**Energy
harvesting from vibration**

**Getting Started with Vibration Energy
Harvesting_V7**

**The
energy
harvesting ****resistor, acting like a linear resistor, has
**

**the ability to
dampening/harvest arbitrary energy waveforms. For
**

**Everything in Nature that can carry a wave of
energy **

**has a characteristic impedance, like a transmission
line.
**

to build a buoy array that terminates ocean waves with their

characteristic impedance such at at least 90% of the energy

is absorbed? And could the energy that gets absorbed be

**harvested by using shock absorbers techniques?
**

Having the ability to dampen shock by harvesting energy

is finding many new applications outside of wave energy.

** The following are some patents and information.**

**6982497_Backpack_for_harvesting_electric
**

**7168532_Wave_energy_converter__WEC__with_Magnetic_Braking**

Perhaps the best feature about this energy harvesting architecture,

is how easy it is to hook up. This
web page shows the first working

prototype being used to transfer energy bidirectionally between

the AC line and two DC supplies. It so happens that pretty much

any power supply which addresses
power factor correction is in

fact operating like a energy
harvesting resistor. But these

other **architectures may not be as simple to build or play
with. **** **

1.3.11_2.44PM

dsauersanjose@aol.com

Don Sauer

http://www.idea2ic.com/