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. 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;
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; 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.
2. The system of claim 1 , further comprising a controller to generate control signals, wherein the input switch operates in response to the control signals.
3. The system of claim 1 , 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.
4. The system of claim 1 , 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.