Supply architecture for inductive loads
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.
1. An apparatus comprising:
a computer program product (CPP) tangibly embodied in a non-transitory computer readable medium and containing instructions that, when executed, cause a processor to perform operations to control energy transfer from an energy supply to a load, the operations comprising:
connect 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;
disconnect the input node from the output node during a remainder of the operating cycle;
control 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, wherein controlling a REMF voltage comprises providing a path for the output current to flow through a voltage limiting circuit;
collect a portion of the energy stored in the magnetic field during the operating cycle in an energy storage element; and
supply the collected energy to the load in a subsequent operating cycle.
2. The apparatus of claim 1 , wherein the operation to control a REMF voltage comprises providing a path for the output current to flow through a voltage limiting circuit.
3. The apparatus of claim 1 , wherein the operation to collect a portion of the energy stored in the magnetic field during the operating cycle comprises an operation to provide a path for the output current to flow through a capacitance.
4. The apparatus of claim 3 , wherein the operation to supply the collected energy to the load in a subsequent operating cycle comprises an operation to transfer 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.
5. The apparatus of claim 3 , wherein the CPP further comprises an operation to adjust the capacitance to cause the output current to fall to substantially zero during the operating cycle.
6. The apparatus of claim 1 , wherein the operation to collect a portion of the energy stored in the magnetic field during the operating cycle comprises an operation to cause the output current to fall to substantially zero during the operating cycle.
7. The apparatus of claim 1 , wherein the output current flows in only one direction with respect to the output node.
8. The apparatus of claim 1 , wherein the source comprises a unipolar voltage source.
9. The apparatus of claim 1 , wherein a duration of each operating cycle is between about 10 and about 20 milliseconds.
10. The apparatus of claim 1 , wherein a duration of each operating cycle is between about 1 and about 30 milliseconds.
11. The apparatus of claim 1 , wherein a duration of each operating cycle is between about 50 and about 1000 microseconds.
12. The apparatus of claim 1 , wherein a duration of each operating cycle is less than 60 microseconds.
13. The apparatus of claim 1 , wherein the CPP further comprises an operation to modulate a capacitance of the energy storage element to discharge the load current to substantially zero before the subsequent operating cycle.