Supply architecture for inductive loads

• US 20070146958A1
• Filed: 10/16/2006
• Published: 06/28/2007
• Est. Priority Date: 12/28/2005
• Status: Active Grant

• Current Assignee: FlyBack Energy, Inc.
• Original Assignee: FlyBack Energy, Inc.
• Inventors: Babcock, Paul M., Smith, Phillip N., Babcock, David J.
• Granted Patent: US 7,602,157 B2
• Time in Patent Office: Days
• US Class Current: 361/160
• CPC Class Codes: H02P 7/281 the DC motor being operated in four quadrants

Abstract

Apparatus and associated systems and methods may relate to a process for supplying unidirectional current to a load, controlling a reverse electromotive force (REMF), capturing inductive energy from the load, and supplying the captured inductive energy to the load. In an illustrative example, an operating cycle may include a sequence of operations. First, inductive energy captured from the load on a previous cycle may be supplied to the load. Second, energy may be supplied to the load from an external power source. Third, a REMF voltage may be substantially controlled upon disconnecting the power source from the load. Fourth, the load current may be brought to zero by capturing the inductive energy for use on a subsequent cycle. In some embodiments, a single power stage may supply a DC inductive load, or a pair of power stages may be operated to supply bidirectional current to an AC load.

Claims

1. A method of controlling energy transfer energy from an energy supply to a load, the method comprising:

connecting an input node to an output node to transfer energy from a source connected to the input node to a magnetic field that is associated with an output current flowing from the output node to a load, the connection being made during a portion of an operating cycle;

disconnecting the input node from the output node during a remainder of the operating cycle;

collecting a portion of the energy stored in the magnetic field during the operating cycle in an energy storage element; and

supplying the collected energy to the load in a subsequent operating cycle.

2. The method of claim 1, further comprising controlling a reverse electromotive force (REMF) voltage associated with the magnetic field by providing a path for the output current to flow when the output node is disconnected from the input node.

3. The method of claim 2, wherein controlling a REMF voltage comprises providing a path for the output current to flow through a voltage limiting circuit.

4. The method of claim 1, wherein collecting a portion of the energy stored in the magnetic field comprises providing a path for the output current to flow through a capacitance.

5. The method of claim 4, wherein supplying the collected energy to the load in a subsequent operating cycle comprises transferring the collected energy from the capacitance to a magnetic field that is associated with the output current flowing from the output node to the load.

6. The method of claim 4, further comprising adjusting the capacitance to cause the output current to fall to substantially zero during the operating cycle.

7. The method of claim 1, wherein collecting a portion of the energy stored in the magnetic field comprises causing the output current to fall to substantially zero during the operating cycle.

8. The method of claim 1, wherein the output current flows in only one direction with respect to the output node.

9. The method of claim 1, further comprising rectifying an alternating current signal to supply energy to the source.

10. The method of claim 1, wherein the source comprises a unipolar voltage source.

11. The method of claim 1, wherein a duration of each operating cycle is between about 10 and about 20 milliseconds.

12. The method of claim 1, wherein a duration of each operating cycle is between about 1 and about 30 milliseconds.

13. The method of claim 1, wherein a duration of each operating cycle is between about 50 and about 1000 microseconds.

14. The method of claim 1, wherein a duration of each operating cycle is less than 60 microseconds.

15. A system to transfer energy between an energy supply and a resistive or inductive load, the system comprising:

at least one power stage, each power stage comprising;

an input connectable to a source having a unipolar voltage;

an output connectable to a load that comprises an inductance;

an input switch operable to connect the input to the output during a first portion and a second portion of a time period, and to substantially isolate the input from the output during other portions of the time period;

an energy capture circuit operable during a third portion of the time period to store inductive energy that is present in the load at the end of the second portion of the time period; and

an energy recovery circuit operable during the first portion of the time period to supply stored energy from the energy capture circuit to the input, wherein the first portion of the time period precedes the second portion of the time period, and the second portion of the time period precedes the third portion of the time period.

16. The system of claim 15, further comprising a voltage limiting circuit operable to limit a voltage associated with the load inductance during a fourth portion of the time period, wherein the fourth portion of the time period extends from the end of the second portion of the time period until the third portion of the time period.

17. The system of claim 15, further comprising a controller to generate control signals, wherein the input switch operates in response to the control signals.

18. The system of claim 15, comprising a first power stage coupled to supply current to the load in a first direction, and a second power stage coupled to supply current to the load in a direction opposite of the first direction.

19. The system of claim 15, comprising a plurality of pairs of power stages coupled to drive a corresponding plurality of loads arranged in a multiple phase system, each pair of power stages comprising:

a first power stage coupled to supply current to a corresponding phase load in a first direction; and

a second power stage coupled to supply current to the corresponding phase load in a direction opposite of the first direction.

20. A system for transferring energy between an energy supply and a resistive or inductive load, the system comprising:

a first switch device that connects and disconnects an input node to an output node in response to a control signal;

a storage device;

a second switch device that connects the output node to the storage device to permit transfer of energy from an inductive load connected to the output node to the storage device when the first switch device disconnects the input node from the output node;

a circuit to transfer energy from the storage device to the load when the first switch device reconnects the input node to the output node.

21. The system of claim 20, further comprising a voltage limiter to limit a voltage generated by the load when first switch device disconnects the input node from the output node.

22. The system of claim 20, further comprising a controller to control a timing of the control signal.

23. An apparatus comprising:

means for supplying unidirectional current to a load such that a reverse electromotive force generated by the load is substantially controlled and such that stored inductive energy from the load is captured each operating cycle and returned to supply unidirectional current to the load on a subsequent operating cycle; and

a controller to generate a signal to cause the supply means to perform a sequence of operations during each operating cycle.

24. The apparatus of claim 23, wherein the controller comprises a memory containing instructions that, when executed by a processor, cause the controller to respond to an input signal by adjusting a timing of the generated signal within each operating cycle.