WO2003014855A2 - Systemes et procedes pour circuit d'alimentation electrique a stockage d'energie - Google Patents

Systemes et procedes pour circuit d'alimentation electrique a stockage d'energie Download PDF

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Publication number
WO2003014855A2
WO2003014855A2 PCT/US2002/024486 US0224486W WO03014855A2 WO 2003014855 A2 WO2003014855 A2 WO 2003014855A2 US 0224486 W US0224486 W US 0224486W WO 03014855 A2 WO03014855 A2 WO 03014855A2
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WO
WIPO (PCT)
Prior art keywords
storage device
power supply
current
circuit
voltage
Prior art date
Application number
PCT/US2002/024486
Other languages
English (en)
Other versions
WO2003014855A3 (fr
Inventor
Perry Faubert
Original Assignee
Novatel Wireless, Inc.
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 Novatel Wireless, Inc. filed Critical Novatel Wireless, Inc.
Publication of WO2003014855A2 publication Critical patent/WO2003014855A2/fr
Publication of WO2003014855A3 publication Critical patent/WO2003014855A3/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H04B1/1607—Supply circuits
    • 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
    • H02J7/345—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering using capacitors as storage or buffering devices

Definitions

  • the invention relates generally to supplying- power to devices requiring high peak currents in systems with limited current power sources and more particularly to systems and methods for an energy storage based power supply circuit.
  • PC cards are used to expand the capabilities of computing devices, particularly laptop computers.
  • One type of PC card that is becoming more and more popular is a wireless modem PC card that can enable wireless data communication anywhere wireless data service is provided.
  • a wireless modem PC card that can enable wireless data communication anywhere wireless data service is provided.
  • PC cards are designed around a standardized interface, such as a PCMCIA interface.
  • the standards used to define such interfaces will often specify important parameters such as the voltage and maximum current supplied by the laptop, or host, to the PC card. Unfortunately, these specified parameters can prove insufficient for certain types of PC cards.
  • the maximum current supplied by the host may be limited to 1 Ampere (A); however, a wireless modem PC card, such as the GPRS G201 PC card from Novatel Wireless, Inc., can require peak currents of as high as 2 A. Obviously, this type of problem requires a solution if such a wireless modem is going to be used with such a host device, and there are several solutions currently practiced.
  • One solution is to include a separate battery on the PC card that is rated to supply the PC card with the required voltage and peak current. But this solution has several drawbacks. First, for example, the PC card requirements can expressly preclude using a separate battery. Second, even if a separate battery can be used, doing so adds significant bill of material cost and requires extra space within the PC card, which may be at a premium. Third, the battery needs to be replaced once it is discharged, or charging circuitry needs to be included, further driving up costs and impacting space requirements.
  • a power supply circuit comprises a current limiter configured to limit a current drawn from a host power supply to a maximum current that is less than a maximum current for the host power supply.
  • the power supply circuit also comprises a storage device coupled to the current limiter. The storage device is configured to store energy for supplementing the current drawn from the host power supply in order to generate a load current that is higher than the maximum current that can be supplied by the host power supply.
  • the power supply circuit also comprises a voltage regulator coupled to the current limiter and the storage device.
  • the voltage regulator is configured to provide the load current and an output voltage to a load device.
  • figure 1 is a logical block diagram illustrating an exemplary wireless modem transmitter
  • figure 2 A is a logical block diagram illustrating an exemplary linear power supply regulator circuit that can be used to supply power to the wireless modem transmitter of figure 1;
  • figure 2B is a circuit diagram illustrating an exemplary circuit for the regulator of figure 2A;
  • figure 2C is a logical block diagram illustrating a conventional method for supplying peak current to the wireless modem transmitter of figure 1;
  • figure 3 is a logical block diagram illustrating one example storage based power supply circuit for supplying power to the wireless modem transmitter of figure 1 in accordance with the invention
  • figure 4 is a logical block diagram illustrating another example storage based power supply circuit for supplying power to the wireless modem transmitter of figure 1 in accordance with the invention.
  • figure 5 is a graph of various waveforms showing the performance of the circuit illustrated in figure 3.
  • FIG. 1 is a logical block diagram illustrating the basic functional blocks of a wireless modem transmitter 100.
  • transmitter 100 includes a processor, sometimes referred to as a baseband processor, that is responsible for digitally encoding data messages for transmission by transmitter 100.
  • the encoded messages are then sent to modulation block 104, which is responsible for modulating the encoded message onto a Radio Frequency (RF) carrier signal.
  • RF Radio Frequency
  • This process can be done in one step, referred to as direct conversion, or in two steps, referred to as Intermediate Frequency (IF) conversion.
  • the modulated RF carrier signal is then sent to Power Amplifier (PA) 106, which amplifies the RF carrier signal to the appropriate power level before it is transmitted over a communication channel via antenna 108.
  • PA Power Amplifier
  • PA 106 is a very important part of transmitter 106. Without PA 106, the signal power at antenna 108 will often be insufficient for the operating ranges required in most wireless communication systems. In order to boost the power of the RF carrier signal, however, PA 106 itself consumes a relatively large amount of power.
  • the GPRS G201 PC card form Novatel Wireless, Inc. is designed to transmit in the GSM band at approximately 2 Watts. This requires 2 A of peak current for a duration of 577 micro-seconds ( ⁇ s) for each transmission time slot. When the G201 PC card is not transmitting, it can draw as much as 200 milli- Amperes (mA). Thus, the average current draw over two transmission slots is:
  • PC cards are small and area is limited, they usually do not include their own power sources, such as a battery.
  • power supply 110 is typically included in the host device in which a PC card is installed.
  • a host power supply of this sort is often unable to supply high peak currents such as that required by the G100 PC card.
  • a host power supply it is not uncommon for a host power supply to only be able to provide 1A at 5 volts (V), or for example a Compact Flash card receives 500mA at 3.3V from the host devie.
  • V 5 volts
  • a Compact Flash card receives 500mA at 3.3V from the host devie.
  • a PC card such as a wireless modem PC card that comprises a transmitter 100.
  • a common approach to interfacing a host power supply to a wireless modem PA is to use a linear regulator.
  • the linear regulator produces a stable voltage at a required level to the PA.
  • a typical linear regulator circuit 200 is shown in figure 2A.
  • circuit 200 comprises a Low Drop Out (LDO) regulator 202.
  • LDO 202 receives as an input the supply voltage (VCC) 208 from the host supply, and generates an output voltage (Vout) 206 that is provided to PA 100.
  • VCC supply voltage
  • Vout output voltage
  • a conventional method of addressing the current limitation of the host device is to use several large capacitors 204 at the output of LDO 202. Before such an approach is discussed in more detail, however, the basic operation of LDO 202 will be explained.
  • an LDO comprises a pass transistor 218, which passes VCC 208 through to Vout 206.
  • An error amplifier 220 drives pass transistor 218.
  • Vout 206 is sampled through a resister divider comprised of resistors 210 and 212. The sampled voltage is then fed into the inverting input of error amplifier 220 at node 216.
  • the non-inverting input is tied to a voltage reference 222, which is preferably an internal bandgap reference.
  • error amplifier 220 will try and force the voltages at it's input to be equal. If the load on Vout changes, then error amplifier 220 will source current as required to maintain the load at the regulated output voltage, which is given by:
  • Vout Vref x (1 + R210/R212)
  • regulator 200 can continue to regulate Vout 206. If VCC drops below this level, then LDO 202 is said to be in drop out and regulator 200 will cease to regulate Vout 206.
  • output capacitor 204 is a key component to the operation of LDO 202.
  • Capacitor 204 is used to provide stability to LDO 202 by preventing the output of LDO 202 form oscillating. Accordingly, the equivalent series resistance (ESR) of capacitor 204 must be within a predetermined range. If the ESR is too high or too low, then the output will oscillate. This usually requires the use of relative large tantalum or aluminum electrolytic capacitors. Tantalum capacitors exhibit more stable ESR over temperature and are therefore preferred in most applications.
  • Low ESR is also desirable to reduce fluctuations in Vout 206, which can reduce the performance of PA 100, for example. These fluctuations can be modeled with the following equation:
  • a common solution is to place several large tantalum capacitors, 224, 226, and 228 (figure 2C), at the output of an LDO that is supplying power to the component requiring the high peak current, e.g., PA 100.
  • an LDO that is supplying power to the component requiring the high peak current
  • one conventional approach is to place three 470 micro-farad ( ⁇ F) tantalum capacitors in parallel at the output of regulator 202 as shown in figure 2C.
  • ⁇ F micro-farad
  • regulator 202 will take over and source the current to PA 100.
  • the current sourced by regulator 202 will be limited, however, by host power supply 110.
  • regulator 202 will only be able to source 1A of current to PA 100 based on the above example.
  • host supply 110 can disconnect or the supply voltage can drop too low for proper modem 200 operation.
  • capacitors 224, 226, and 228 will again start to source current to PA 100. But this means the voltage on capacitors 224, 226, and 228 will start to drop again as they are further discharged. Unfortunately, the voltage on capacitors 224, 226, and 228 will often drop too fast.
  • FIG. 3 provides a logical block diagram of an example energy storage based power supply circuit 300.
  • Power supply circuit 300 comprises a voltage regulator 302, with output storage device 304, configured to supply power to PA 306, which will then amplify and transmit RF signals via antenna 308.
  • Regulator 302 can be an LDO and output storage device 304 can be a capacitor configured to supply stability to regulator 302 and to supply the initial peak current to PA 306 as described above.
  • regulator 302 can be any regulator appropriate in wireless modem PA power supply circuit design, e.g., a switch mode power supply circuit.
  • circuit 300 also comprises current limiter 310 and storage device 312 coupled to the input of regulator 302 as shown in figure 3. Current limiter 310 limits the current drawn from the host device.
  • current limiter 310 can be configured to limit the current drawn from host power supply 314 to 800mA, i.e., 1A - 200mA - 800mA.
  • the device or circuit that requires a high peak current can draw the current directly from the combination of current limiter 310 and storage device 312.
  • the systems and methods described herein do not necessarily require regulator 302 and/or output storage device 304.
  • the peak current can be supplied from storage device 312 alone. It should also be noted that some or all of the component devices comprising circuit 300 can reside in the host device.
  • Storage device 312 is configured to store enough energy to supplement the current from current limiter 310 so as to meet the peak current requirement of PA 306.
  • storage device 312 is a large tantalum capacitor or parallel series of large tantalum capacitors.
  • storage device 312 can be 4 parallel 470 ⁇ F tantalum capacitors.
  • the amount of storage provided by storage device 312 will dictate how long PA 306 can transmit without its supply voltage level falling below the minimum operating level for PA 306.
  • the amount of storage provided by storage device 312 will depend on the particular implementation.
  • regulator 302 can be a buck/boost switch mode power supply in which case storage device 312 can be charged to a voltage that is higher and discharge to a voltage that is lower than the required output voltage.
  • regulator 302 can be configured to supply a regulated output voltage that is higher, lower, or the same as the voltage on storage device 312.
  • current limiter 310 uses the maximum power from host power supply 314 at all times. Thus, the power from storage device 312 is only used to supplement the power supplied by host power supply 314 through current limiter 310. This means that the supply voltage for PA 306 will drop at the slowest possible rate.
  • current limiter 310 will charge storage device 312 at the maximum rate possible, i.e., at 800mA, meaning that storage device 312 is charged in the minimum amount of time possible.
  • PA 306 will be ready to transmit again in the shortest amount of time possible.
  • current limiter 310 does not need to be fed information as to when PA 306 is on, i.e., high peak current demand, or off, i.e., non-peak current demand. This is advantageous relative to alternative embodiments of circuit 300, which will be discussed below.
  • current limiter 310 provides safety from the standpoint that if storage device 312, or some portion thereof, were to fail, then the power supplied to storage device 312 is cutoff.
  • storage device 312 comprises one or more tantalum capacitors and one is shorted out
  • current limiter 310 will automatically limit the current supplied to the short. The short will cause current limiter 310 to dissipate more power than normally, which will cause current limiter 310 to heat up.
  • current limiter 310 includes a thermal switch so that as it heats up, the thermal switch will open and remove power from the capacitors. The result is a fail-safe condition.
  • circuit 300 a key design limitation on circuit 300, however, can be that the average current required by the wireless modem PC card should not exceed the maximum current rating for host power supply 314
  • FIG. 4 illustrates an alternative embodiment in which current limiter 310 is replaced with control circuit 400.
  • Control circuit 400 comprises a switch 404, in this case a Field Effect Transistor (FET), that is controlled by control signal 412.
  • FET Field Effect Transistor
  • control signal 412 enables FET 404, i.e., control signal 412 is low, then storage device 312 is charged from host supply 410 through FET 404.
  • control circuit 400 includes resistor 406 in series with FET 404 so that storage device 312 is charged through FET 404 and resistor 406. Resistor 406 can be selected so as to limit the maximum charge current supplied to storage device 312 when PA 306 is off according to the following equation:
  • R406 [(VCCmax - V312min)/Iccmax] - RDS404; where VCCmax is the maximum charge voltage;
  • ICCmax is the maximum charge current
  • RDS404 is the drain-source resistance of FET 404.
  • control signal 412 will preferably go low enabling FET 404 when PA 306 is off.
  • control signal 412 will disable FET 404, i.e., go high, preventing storage device 312 from charging any further.
  • Storage device 312 will then begin sourcing current to PA 306. Therefore, when the voltage on storage device 312 drops to the level of host power supply 410, host power supply 410 will begin to source current to PA 306.
  • control circuit 400 includes diode 408, or some other device, so that current will not flow from power supply 410 until the voltage on storage device 312 has dropped below that of host power supply 410 by some predetermined amount, e.g., an amount equal to a diode voltage drop.
  • Diode 408 can be a silicon diode, a Schottky diode, or some combination of diodes and diode types as required.
  • circuit 400 allows storage device 312 to discharge to a minimum level without drawing more than a maximum allowable current from host power supply 410. Thus, the amount of storage included in storage device 312 must be selected with this in mind.
  • Trace 502 represents the measured voltage supplied by the 5V host power supply 314.
  • Trace 504 illustrates the measured voltage on storage device 312.
  • Trace 506 illustrates the measured current drawn from supply 314.
  • Trace 508 illustrates the measured voltage at the output of regulator 302, which is the supply voltage for PA 306.
  • Three time periods are also referenced in figure 5: time period 510 during which PA 306 is on, time period 512 during which PA 306 is off, and time period 514, which is the combined on/off time period.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

L'invention concerne un circuit d'alimentation électrique comprenant un limiteur de courant configuré pour limiter un courant tiré d'une alimentation électrique hôte à un niveau de courant maximum inférieur au niveau de courant maximum pour l'alimentation électrique hôte. Le circuit d'alimentation électrique comprend également un dispositif de stockage couplé au limiteur de courant. Ledit dispositif de stockage est configuré pour stocker de l'énergie en vue de compléter le courant tiré de l'alimentation électrique hôte afin de produire un courant de charge supérieur au courant maximum pouvant être fourni par l'alimentation électrique hôte. Ledit circuit d'alimentation électrique comprend également un régulateur de tension couplé au limiteur de courant et au dispositif de stockage. Ledit régulateur de tension est configuré pour fournir le courant de charge et une tension de sortie à un dispositif de charge.
PCT/US2002/024486 2001-08-08 2002-08-02 Systemes et procedes pour circuit d'alimentation electrique a stockage d'energie WO2003014855A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US92523801A 2001-08-08 2001-08-08
US09/925,238 2001-08-08

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WO2003014855A2 true WO2003014855A2 (fr) 2003-02-20
WO2003014855A3 WO2003014855A3 (fr) 2003-11-06

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004023637A1 (fr) 2002-09-09 2004-03-18 Energy Storage Systems Pty Ltd Systeme d'alimentation
WO2004049145A1 (fr) * 2002-11-27 2004-06-10 Sierra Wireless, Inc. Ecreteur de courant adaptatif pour modem sans fil
CN114268146A (zh) * 2021-12-07 2022-04-01 成都长城开发科技有限公司 低温环境下电子仪表的供电装置、方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4092709A (en) * 1976-09-24 1978-05-30 Texas Instruments Incorporated Multiple output self oscillating converter regulator power supply

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4092709A (en) * 1976-09-24 1978-05-30 Texas Instruments Incorporated Multiple output self oscillating converter regulator power supply

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004023637A1 (fr) 2002-09-09 2004-03-18 Energy Storage Systems Pty Ltd Systeme d'alimentation
EP1665512A1 (fr) * 2002-09-09 2006-06-07 Energy Storage Systems Pty, Ltd. Systeme d'alimentation
EP1665512A4 (fr) * 2002-09-09 2008-02-20 Cap Xx Ltd Systeme d'alimentation
WO2004049145A1 (fr) * 2002-11-27 2004-06-10 Sierra Wireless, Inc. Ecreteur de courant adaptatif pour modem sans fil
US7106569B2 (en) 2002-11-27 2006-09-12 Sierra Wireless, Inc. Adaptive current limiter for wireless modem
US7586724B2 (en) 2002-11-27 2009-09-08 Sierra Wireless, Inc. Adaptive current limiter for wireless modem
CN114268146A (zh) * 2021-12-07 2022-04-01 成都长城开发科技有限公司 低温环境下电子仪表的供电装置、方法
CN114268146B (zh) * 2021-12-07 2024-02-13 成都长城开发科技股份有限公司 低温环境下电子仪表的供电装置、方法

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