GB2456299A - Pseudo-resistive converter - Google Patents

Pseudo-resistive converter Download PDF

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Publication number
GB2456299A
GB2456299A GB0800238A GB0800238A GB2456299A GB 2456299 A GB2456299 A GB 2456299A GB 0800238 A GB0800238 A GB 0800238A GB 0800238 A GB0800238 A GB 0800238A GB 2456299 A GB2456299 A GB 2456299A
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GB
United Kingdom
Prior art keywords
power converter
electrical power
switch
input
switching
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB0800238A
Other versions
GB0800238D0 (en
Inventor
Robin Tingey
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to GB0800238A priority Critical patent/GB2456299A/en
Publication of GB0800238D0 publication Critical patent/GB0800238D0/en
Publication of GB2456299A publication Critical patent/GB2456299A/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/14—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle
    • H02J7/1415—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle with a generator driven by a prime mover other than the motor of a vehicle
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/34—Conversion of dc power input into dc power output with intermediate conversion into ac by dynamic converters
    • H02M3/38—Conversion of dc power input into dc power output with intermediate conversion into ac by dynamic converters using mechanical contact-making and -breaking parts to interrupt a single potential
    • H02M3/42—Conversion of dc power input into dc power output with intermediate conversion into ac by dynamic converters using mechanical contact-making and -breaking parts to interrupt a single potential with electromagnetically-operated vibrating contacts, e.g. chopper
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators

Abstract

An electrical power converter comprising an inductor 3, an oscillator 1 which operates a first switch 2, and a diode 4 or second switch to the output. The electrical power converter gives a pseudo resistive input characteristic which is intrinsic to its switched inductor operation and does not require feedback, though feedback can be used to modify its characteristic. As the supplied input voltage is increased, the input current also increases. The output characteristic is to deliver an energy pulse as the inductor is de-energised. This device can be used to provide maximum power point tracking of a generator 5 without needing the intelligence of a microprocessor if the characteristics of the generator, converter and load 6 are matched.

Description

Page 1
DESCRIPTION
PSEUDO RESISTIVE CONVERTER
Background
Wind turbines are often used to provide power in remote locations. As the power rarely matches the usage, the power is stored in batteries. Under low energy conditions it is possible for the generator to be turning but insufficient voltage is available to charge the batteries. If the generator is run into deliberately lower voltage batteries then this can improve the yield under low energy conditions, but can have the adverse drawback of reducing performance during high energy conditions due to the generator being overloaded.
The purpose of the invention is to provide optimum loading to the generator for charging the batteries. Other types of multi power point tracker already exist that use pulse width modulation techniques to adjust the voltage applied to the generator but suffer from the following disadvantages: 1) The optimum set point is difficult to determine as the generator will change its speed according to the load applied and also as conditions vary. It is much better to present a resistance rather than a load voltage as this can be held steady under all conditions.
2) Intelligent maximum power point trackers require sophisticated microprocessors and software which also add to the cost, reliability, size, power consumption, etc. 3) Maximum power point trackers operate off the battery and consume power even when there is no generation.
4) If the regulating switch transistor fails, the generator will be presented with an open circuit which can result in it rotating too fast causing a dangerous mechanical failure.
Mode of Operation An inductor3 is energised whilst it is connected across a generator5 by means of an electronically operated switch2. The switch2 is closed for a period set by an oscillator', and during that period the rate of rise in current through the inductor3 is proportional to the voltage supplied by the generator3. A diode4 is used to prevent current flowing back from the load6 whilst the switch2 is closed. When the switch2 is opened, the current through the inductor3 is diverted to the load6. If the generator5 voltage is less than the load6 voltage multiplied by the switch2 off duty cycle, then the current through the inductor3 will decay to zero before the switch2 off period completes. The average current will increase as the generator voltage increases. The increase in current is not perfectly linear as the duration of conduction whilst the switch is off will also increase with increasing generator voltage.
If the generator5 voltage is more than the load6 voltage multiplied by the switch2 off duty cycle, then the current through the inductor3 will still be flowing when the switch2 off period completes. This will allow the average current to increase limited only by the capability of the generator5. The input characteristic of the converter in this mode becomes constant voltage. This can be a useful characteristic to prevent excessive generator speed and also ensure that maximum loading is available under strong generation conditions (e.g. windy weather if the generator is a wind turbine). The start up resistance may be set deliberately high to facilitate easy starting or easy acceleration, but this resistance may be too high to be appropriate for strong generation conditions. It is also possible to modify the converter characteristics by simply varying the switch frequency or duty cycle. These can be preset to suit a particular application or even dynamically varied during operation of the converter.
Page 2
PSEUDO RESISTIVE CONVERTER
Example embodiments of the invention: Figure A shows the basic topology essential for the operation of the invention.
Figure B shows an alternative topology that is more linear as there is no generator5 current when the switch2 is off. It has the disadvantage that should the switch2 fail, then the generator5 will be presented with an open circuit. The threshold where the input transitions from pseudo resistive to fixed voltage mode is also different, it is the load6 voltage times the switch2 off duty cycle and divided by the switch2 on duty cycle. For this topology, the resistance presented to the input in resistive mode is calculated as: R= Figure C shows the circuit diagram of an actual working prototype that is in operation.
Figure C detailed description:
The type of generator5 is a Futurenergy FE! 048U which is designed to operate into a 48V battery bank. This features 5 blades, a permanent magnet alternator and integral rectifier.
The inductor5 used is a 64uH air core torroid.
The switch2 used is a Fairchild Semiconductor FDP3632 high power MOSFET.
The output diode4 is a MBR3O6OPT dual schottky diode, connected in parallel.
The output load6 is a 48V 15OAH deep cycle lead acid battery bank.
The oscillator' used is a 1CM7556 dual timer. One half is conneàted as an astable with pins 8 and 12 both connected to a 330pF grounded capacitor. The capacitor is charged via two l2OKohm resistors connected in series to pin 14. The capacitor is discharged via one of the l2OKohm resistors into pin 13. The charging and discharging cycles are controlled by thresholds at pins 8 & 12. The output from that timer half on pin 9 is inverted by the other half, using pins 6 & 2 as inputs. Pin 4 is used to disable the oscillator when the battery voltage is more than 60V or the generator5 voltage is below approx I 2V. Pins 3 and 11 are decoupled to ground via a 3.9nF capacitor to stabilise the timer switching thresholds.
The oscillator' output from pin 5 is fed to the switch2 via a buffer amplifier'0 in order to boost the current and reduce the switching transition time. The buffer amplifier used is made of a BD 139 and BD 140 bipolar transistor complementary pair connected as emitter followers.
The converter input has smoothing capacitors7 to reduce noise transmission and provide a low dynamic impedance to the converter. This comprises a 0.47uF I OOV paper capacitor and two l000uF!OOV electrolytic capacitors wired in parallel to make a 2000uF capacitor.
The converter output has smoothing capacitors8 to reduce noise transmission and provide a low dynamic impedance to the converter. This comprises a 0.47uF 1 OOV paper capacitor and two 1 000uF 1 OOV electrolytic capacitors wired in parallel to make a 2000uF capacitor.
Page 3
PSEUDO RESISTIVE CONVERTER
The oscillator' is supplied power from the generator5 via a linear adjustable voltage regulator9 which prevents excessive voltage reaching the oscillator1. The type of voltage regulator9 is a LM3 1 7T, it is set to 1 6V using a 22Oohm resistor between its output and its adjust pin, and a 2.7Kohm resistor is connected from the adjust pin to ground. It has 4.7uF capacitor on the input and a 22uF capacitor on the output. The voltage regulator9 is also used to supply power to a dual operational amplifier which forms part of the output over voltage circuit'2.
The type of operational amplifier used is a TL072 dual low noise FET input.
The output over voltage circuit'2 compares the Load6 voltage (which is reduced using a high impedance adjustable potential divider'3) against a reference formed by a zener diode. If the Load6 voltage is too high a dump load'5 will be switched on using another switch'4 and the oscillator' will also be disabled. To prevent accidental switching of the dump load'5 due to the reference zener not having full voltage due to low generator5 voltage, a zener diode is included in the path from the output over voltage circuit12. A 33Oohm resistor is also included in series to slow down the switching time and reduce generated interference. A 22Kohm resistor is connected between the dump load'5 switch'4 gate and ground to ensure it is off and not floating unless explicitly switched on.
All zener diodes in this circuit are 5.6V, which was chosen due to its low temperature coefficient. The reference zener diode used in the output over voltage circuit'2 is powered via a 2.2Kohm resistor and AC decoupled to ground with a lOnF capacitor. The operational amplifier that does the comparison has a 47OnF capacitor and lMohm resistor in series between its positive input and output so that delay hysterisis slows down any decision oscillations that could cause the dump load'5 switch'4 to dissipate excessive heat or cause the oscillator' to give strange duty cycles.
The connection from the output over voltage circuit'2 to the oscillator' has two zener diodes in series to prevent the oscjllator' from operating when the generator5 voltage is below about 12V. A 6.8Kohm resistor is used to pull the reset input (pin 4 on the oscillator') low when the zener diodes are not conducting.
All the converter power components are mounted on a heat sink, which also has a fan'6 driven by the generator5. The fan'6 is operated via a simple regulation circuit so that its maximum operating voltage is not exceeded. The fan regulator consists of two zener diodes in parallel with a 1.5Kohm resistance and fed by a l.8Kohm resistance connected to the generator5. This forms a reference voltage that is amplified by a BD139 NPN emitter follower to supply a 12V DC brushless fan.
The performance of this embodiment has been measured as follows: Input Voltage Input Current Input Power Output Voltage Output Current Output Power Efficiency 12.84 0.53 6.81 52.3 0.11 5.75 0.85 14.93 1.45 21.65 47.8 039 10.64 0.06 25.7 2.9 74.53 52 1 1.39 72.42 0.97

Claims (18)

  1. Page Lt
    PSEUDO RESISTIVE CONVERTER
    I. An electrical power converter where a continuously switched inductor provides an intrinsic pseudo resistive input characteristic and an energy pulse output via a diode or another switch when the inductor switch opens.
  2. 2. An electrical power converter as claimed in claim 1 where the power to perform the switching is derived from the input.
  3. 3. An electrical power converter as claimed in claim I or claim 2 where the switch duty cycle is varied as the input voltage changes.
  4. 4. An electrical power converter as claimed in claim I or claim 2 or claim 3 where the switch frequency is varied as the input voltage changes.
  5. 5. An electrical power converter as claimed in either of claims 1 to 4 where the switching is performed by any kind of electronically operated switch such as a relay or transistor or valve.
  6. 6. An electrical power converter as claimed in either of claims 1 to 4 where the switching is performed by the mechanical rotating or oscillating operation of a switch.
  7. 7. An electrical power converter as claimed in either of claims I to 6 where additional components or complete converters are operated in parallel to perform the same function.
  8. 8. An electrical power converter as claimed in claim 7 where the parallel converters are synchronised to smooth the current flow.
  9. 9. An electrical power converter substantially as herein described and illustrated in the accompanying drawings.
  10. 10. An electrical power converter where an inductor is connected across the input and then connected across the output in repeating cycles.
  11. 11. An electrical power converter where an inductor is connected across the input and then connected in series with the input and the output in repeating cycles.
  12. 12. An electrical power converter as claimed in claim 11 or claim 10 where the power to perform the switching is derived from the input.
  13. 13. An electrical power converter as claimed in claims 10 to 12 where the switch duty cycle is varied as the input voltage changes.
  14. 14. An eiectricai power converter as claimed in claims 10 to 13 where the switch frequency is varied as the input voltage changes.
  15. 15. An electrical power converter as claimed in either of claims 10 to 14 where the switching is performed by any kind of electronically operated switch such as a relay or transistor or valve.
  16. 16. An electrical power converter as claimed in either of claims 10 to 14 where the switching is performed by the mechanical rotating or oscillating operation of a switch.
  17. 17. An electrical power converter as claimed in either of claims 10 to 16 where additional components or complete converters are operated in parallel to perform the same function.
  18. 18. An electrical power converter as claimed in claim 17 where the parallel converters are synchronised to smooth the current flow.
GB0800238A 2008-01-08 2008-01-08 Pseudo-resistive converter Withdrawn GB2456299A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0800238A GB2456299A (en) 2008-01-08 2008-01-08 Pseudo-resistive converter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0800238A GB2456299A (en) 2008-01-08 2008-01-08 Pseudo-resistive converter

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GB0800238D0 GB0800238D0 (en) 2008-02-13
GB2456299A true GB2456299A (en) 2009-07-15

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GB0800238A Withdrawn GB2456299A (en) 2008-01-08 2008-01-08 Pseudo-resistive converter

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5977753A (en) * 1998-01-23 1999-11-02 Astec International Limited Buck regulator with plural outputs
US20030090244A1 (en) * 2001-11-05 2003-05-15 Krishna Shenai Multislice DC-DC converter
US20070075687A1 (en) * 2005-09-30 2007-04-05 Takuya Ishii Buck-boost converter
WO2007049198A1 (en) * 2005-10-27 2007-05-03 Koninklijke Philips Electronics N.V. A system for driving a constant current load
US20070236155A1 (en) * 2006-04-11 2007-10-11 Beyond Innovation Technology Co., Ltd. Power converter for led module and related devices thereof

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5977753A (en) * 1998-01-23 1999-11-02 Astec International Limited Buck regulator with plural outputs
US20030090244A1 (en) * 2001-11-05 2003-05-15 Krishna Shenai Multislice DC-DC converter
US20070075687A1 (en) * 2005-09-30 2007-04-05 Takuya Ishii Buck-boost converter
WO2007049198A1 (en) * 2005-10-27 2007-05-03 Koninklijke Philips Electronics N.V. A system for driving a constant current load
US20070236155A1 (en) * 2006-04-11 2007-10-11 Beyond Innovation Technology Co., Ltd. Power converter for led module and related devices thereof

Also Published As

Publication number Publication date
GB0800238D0 (en) 2008-02-13

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