Electrical apparatus

• US 3,909,685 A
• Filed: 10/16/1974
• Issued: 09/30/1975
• Est. Priority Date: 01/14/1974
• Status: Expired due to Term

• Current Assignee: Lawrence H. Bannister, Richard H. Baker
• Original Assignee: Lawrence H. Bannister, Richard H. Baker
• Inventors: Baker, Richard H., Bannister, Lawrence H.
• Primary Examiner(s): Schaefer, Robert K.
• Assistant Examiner(s): Redman, John W.
• Application Number:
  US05/515,290
• Time in Patent Office: 349 Days
• Field of Search: 328/26,260,264 307/117,43,44,58,82,133,151 318/139 321/5,43,44 320/2-14
• US Class Current: 318/139
• CPC Class Codes: B60L 58/19 Switching between serial connection and parallel connection of battery modules
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: H02M 7/49 Combination of the output voltage waveforms of a plurality of converters
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Electrical apparatus wherein a plurality of batteries, for example, are controllably interconnected to form a power unit which accepts electric energy in a charging mode and feeds a load in a discharging mode. Controllers act through switches to interconnect the batteries in a way that permits them to accept unrectified electric energy from an a-c primary source the voltage and frequency of which may be variable; the energy is accepted over a substantial portion of the power cycle and the rate of charging is controllable; the controllers also interconnect the batteries in a way that permits the power unit to deliver energy to a load at a specified voltage and frequency. The power unit output can, for instance, be 60 cycle a-c, single or three phase. Thus, for example, the primary source can be a windmill-powered or water-powered generator whose output is a sinusoidal voltage that varies with wind or water velocity both in voltage and frequency and the power unit (or more probably a plurality of power units) can be used to provide 60 cycle single phase voltage for domestic use. In general, the batteries are charged in series and a controlled charging rate is maintained by a novel scheme for interconnection in a programmed fashion. The power unit can accept electric energy and feed a load as alternate conditions of operation, or a plurality of power units can be used to give simultaneous charge and feed; and the power unit can be employed as a substitute for the generator or other primary source, that is, to perform the function of an uninterruptable power supply (UPS). As a further example, the concept of changing roles can be employed in electric vehicle drives wherein the power unit electrically powers an a-c electric machine which acts as a motor during acceleration of the vehicle and as a generator during deceleration; the power unit feeds the motor at a variable voltage and variable frequency and accepts electric energy from the generator, again at variable voltage and variable frequency.

Claims

1. Apparatus that comprises a variable-voltage variablefrequency electric power unit that includes a plurality of stages connected in cascade, each stage having supply voltage means, first bilateral switch means and second bilateral switch means, the first bilateral switch means and the second bilateral switch means acting in combination such that the input of the stage and the output of the stage are shorted together and therefore at equal potential, or said supply voltage means is connected between the input and the output such that the output is positive with respect to the input or the output is negative with respect to the input, the supply voltage means in at least one of the stages of the plurality of stages comprising a switched source assembly having a plurality of electric sources that act in concert through electrical interconnection as the supply voltage means of said one of the stages, and means for changing the interconnectioN of the plurality of electric sources in the switched source assembly, thereby to alter in a determined fashion the voltage and the current available from the switches source assembly and hence from said apparatus.

2. Apparatus as claimed in claim 1 in which the supply voltage means and the electric sources comprise rechargable batteries and in which electric energy passes through the same power ports of the power unit in both a charging mode of power unit operation and a discharging mode of power unit operation.

3. Apparatus as claimed in claim 2 that includes controller means which acts to sequence the first bilateral switch means, the second bilateral switch means and the means for changing the interconnection of the plurality of electric sources in a pattern that provides at the power ports of the power unit a time-varying waveform whose amplitude and frequency can be varied under the control of the controller means in a way that effects controllable transfer of electric energy to and from the power unit at said power ports.

4. Apparatus as claimed in claim 3 that further includes charging means connected to the power ports of the power unit, signals indicative of the instantaneous voltage output of the charging means being connected as input to the controller means, the controller means acting in response to said signals to provide an instantaneous voltage output of the power unit that bears the proper relationship to the instantaneous voltage output of the charging means required to effect the desired energy transfer.

5. Apparatus as claimed in claim 4 in which the charging means is a primary source of electric energy having a time varying voltage waveform, the power unit, under the direction of the controller means, providing a voltage waveform at said power ports that approximates that of the primary source and bears a relationship thereto such that the batteries are charged in the charging mode over a substantial fraction of the power cycle of the primary source.

6. Apparatus that includes a plurality of the power units claimed in claim 5 connected in a polyphase configuration and in which the primary source is of the same polyphase configuration.

7. Apparatus as claimed in claim 5 in which the time-varying voltage waveform of the primary source is sinusoidal and the time-varying voltage waveform of the power unit is quasi-sinusoidal.

8. Apparatus as claimed in claim 7 in which the time-varying voltage waveform of the primary source varies in a pseudo-random fashion both as to voltage and as to frequency.

9. Apparatus having a plurality of the variable-voltage, variable-frequency power units of claim 3 interconnected to form a stored-energy processor and that includes processor switch means that acts in concert with the switch means of each power unit, under the direction of the controller means, such that the processor can receive unrectified a-c electric energy over a substantial fraction of the power cycle of the source of such a-c electric energy, and can process and store the energy such that it can subsequently be delivered to the processor power ports at the same or different frequency and/or the same or different voltage as that of said source.

10. Apparatus having a plurality of stored-energy processors of claim 9 interconnected to form a stored-energy system and that includes system switch means that acts in concert with the processor switch means and the switch means of each power unit, under the direction of the controller means, such that the system can receive unrectified a-c electric energy over a substantial fraction of the power cycle of the source of such a-c electric energy and can process and store the energy such that it can subsequently be delivered to the system power ports at the same or different frequency and/or the same or different voltage as that of said source.

11. Apparatus having a plurality of the stored-energy systems of claim 10 interconnected to form a stored-energy grid and that includes grid switch means that acts in concert with the system switch means, the processor switch means and the switch means of each power unit, under the direction of the controller means, such that the grid can receive unrectified a-c electric energy over a substantial fraction of the power cycle of the source of such a-c electric energy, can process and store the energy such that it can subsequently be delivered to the grid power ports at the same or different frequency and/or at the same or different voltage as that of said source.

12. Apparatus as claimed in claim 3 that further includes an electric machine electrically powered by the power unit and adapted to receive electric energy from the power unit during one portion of an operating cycle and to deliver electric energy to the power unit during another portion of the operating cycle, said machine acting as an electric motor during the first-mentioned portion of the cycle and as a generator during the second-mentioned portion of the cycle to recharge the batteries.

13. Apparatus as claimed in claim 12 having feedback means connected from the terminals of the said machine as an input to the controller means permitting control of said interconnection such that there results a controllable transfer of electric energy from said power unit to said machine when the machine is acting as a motor and from said machine to the power unit when the machine is acting as a generator.

14. Apparatus as claimed in claim 13 in which said machine is the prime mover of an electrically-driven vehicle, said machine acting as a motor during acceleration of the vehicle and as a generator during deceleration of the vehicle and which further includes means for controlling the speed of the vehicle, the latter means being connected as a further input to the controller means to influence electric energy transfer between the power unit and said machine.

15. Apparatus as claimed in claim 14 in which a plurality of power units is connected to provide polyphase power and in which said machine is a polyphase machine, means being further provided to permit the plurality of power units to connect to a single-phase or to a polyphase source of electric energy for battery charging.

16. Apparatus as claimed in claim 3 that includes a primary source of electric energy and a load connected to receive an input from the primary source and an input from the power unit, and that further includes means for quickly shifting the input to the load from the primary source to the power unit to prevent interruption of power to the load.

17. Apparatus as claimed in claim 16 in which the means for shifting comprises load switching means that acts to transfer the load from the primary source to the power unit during transient and long-term outages of the primary source.

18. Apparatus as claimed in claim 16 in which the primary source of electric energy is a source of sinusoidal, a-c power, signals indicative of the instantaneous voltage of the primary source being connected as input to the controller means, the controller means acting in response to said signals to provide an instantaneous voltage at the power ports of the power unit relative to the instantaneous voltage of the primary source such that controllable energy transfer between the source and the power unit is effected, said transfer occurring over a substantial fraction of the power cycle of the primary source.

19. Apparatus as claimed in claim 3 that includes a primary source of electric energy, a load connected to receive an input from the primary source and from the power unit, the primary source being connected to deliver electric energy to both the load and the power unit, and means interconnecting the three circuit elements comprising the primary source, the load, and the power unit such that electric current can flow from the primary source to the power unit and to the load and from the power unit to the load, said means for interconnecting being capable, as well, of electrically isolating the three circuiT elements, thereby to permit the power unit to act as an active filter that assumes load bearing duties in the event of short-term or long-term failure of the primary source.

20. Apparatus as claimed in claim 3 that further includes a primary source and a load, the primary source and the power unit being connected in parallel and to the load, the power unit being adapted to receive electric energy from the primary source and to deliver electric energy to the load through the same power ports, the power unit thereby acting as an active filter for short-term and long-term power transients.

21. Apparatus as claimed in claim 20 that further includes comparator means, a reference source connected as one input to the comparator means, a feedback signal from the load connected as the other input to the comparator, the comparator output being connected as input to the controller means to control the transfer of electric energy to and from the power unit.

22. Apparatus as claimed in claim 3 that includes a-c generating means whose output voltage and frequency are randomly variable, connected to the power ports of the power unit, said a-c generating means acting as a source of charging energy for the batteries, feedback means being connected between the generating means output and the controller means to provide a signal to the controller means indicative of the instantaneous voltage output of the generating means, the controller means acting to provide interconnection of batteries in a pattern whereby the instantaneous voltage of the time-varying voltage waveform output from the power unit at all times bears a controllable relationship to the instantaneous voltage of the generator, thereby to allow the batteries to accept unrectified electric energy from the generating means over a substantial fraction of the power cycle of the generating means and to permit a controllable charging rate for the batteries.

23. Apparatus as claimed in claim 22 in which the a-c generating means is a generator driven by a windmill whose angular velocity varies over a wide range of values.

24. Apparatus as claimed in claim 1 in which the plurality of electric sources in the switched source assembly comprises a plurality of energy storage cells and in which the switched source assembly further includes controllable switched source assembly switch means operable to connect all or any portion of the cells in compatible series, parallel and/or series-parallel configurations to alter the voltage and current available from the switched source assembly.

25. Apparatus as claimed in claim 24 in which the supply voltage means in all the stages and including the energy storage cells are electric storage batteries.

26. Apparatus as claimed in claim 25 in which the switched source assembly switch means is a plurality of bilateral switches and that includes switched source assembly controller means to program the interconnection of the batteries in the switched source assembly.

27. Apparatus as claimed in claim 26 that includes power-unit-controller means to program the first bilateral switch means and the second bilateral switch means.

28. Apparatus as claimed in claim 27 that further includes a primary source of electric energy connected as input to the power unit and master controller means that acts to program the power-unit controller means and the switched source assembly controller means, such that the apparatus can accept electric energy from said primary source or, as an alternate condition of operation, can deliver electric energy to a load or back to the primary source, said load having the same or different electrical characteristics relating to frequency, voltage and current, as the primary source.

29. Apparatus in which a plurality of the variable-voltage, variable frequency power units of claim 24 are connected in polyphase configuration, and that includes as a load a polyphase electric motor connected to receive as input thereto the output of the polyphase-connected power units aNd that further includes controller means operable to sequence the power units in a way that provides a polyphase output from the interconnected power units, the controller means acting to effect changes in the voltage and frequency of the polyphase output thereby to permit control of the velocity of the motor.

30. Apparatus as claimed in claim 29 in which the electric motor is the prime mover of an electric vehicle and in which the motor acts automatically, during periods of deceleration of the vehicle, as a generator, thereby to return electric energy to the batteries, the controller means acting to permit the generator to return the electric energy at any frequency and any voltage.

31. Apparatus that comprises a power unit having two electrical power unit ports, said power unit comprising a plurality of stages connected in cascade, each stage having battery means, first bilateral switch means, second bilateral switch means, the first bilateral switch means and the second bilateral switch means acting in combination such that an input terminal of the stage and an output terminal thereof are shorted together and therefore at equal potential, or said battery means is connected between the two terminals such that one terminal is positive with respect to the other terminal or one terminal is negative with respect to the other terminal;

the battery means in at least one of the stages comprising a plurality of batteries and assembly switch means that acts to interconnect the plurality of batteries in a controllable fashion;

said apparatus further including controller means to control the first switch means and the second switch means of each stage of the plurality of stages in a pattern that provides a time-varying waveform at the power unit ports, said controller means being further adapted to control interconnection of the batteries in said at least one of the stages to control the instantaneous voltage of said time-varying waveform.

32. Apparatus that comprises a plurality of batteries, associated bilateral switch means, controller means, said switch means being operable to interconnect the batteries, said controller means acting to program the operation of the switch means so that interconnected batteries provide a time-varying waveform at the power ports of the apparatus, and means for charging the batteries connected to said power ports, said controller means acting to allow the batteries to be charged by controlling the interconnection of the batteries so that resulting instantaneous voltage at said power ports from the plurality of batteries differs from the instantaneous voltage of the source of electric energy connected to effect charging by a small controllable difference voltage Delta V, changes in Delta V being effected under the direction of the controller means to establish a desired level of power flow between the means for charging and the batteries being charged.

33. An electric power unit that comprises, in combination, a plurality of electric storage batteries, switch means that acts to interconnect the storage batteries and controller means that acts to direct the switching pattern of the switch means so that the interconnected batteries present to the power ports of the power unit a periodic voltage waveform whose magnitude and frequency are controllably variable to permit, among other things, the regulation of energy flow at said power ports both as to direction of energy flow and magnitude of energy flow.