Method and apparatus for current shaping in electronically commutated motors
First Claim
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1. A method for shaping current in an electronically commutated motor (ECM) comprising:
- acquiring a set of terminal voltage measurements;
estimating an instantaneous rotor angle from said terminal voltage measurements;
generating a set of phase current commands from said instantaneous rotor angle and from a torque reference signal, each of said phase current commands comprising at least one ripple compensation command segment and at least one zero current command segment; and
converting said set of phase current commands to a set of current reference signals.
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Abstract
A method and apparatus are disclosed for shaping current in an electronically commutated motor (ECM), the method comprising: acquiring a set of terminal voltage measurements; estimating an instantaneous rotor angle from the terminal voltage measurements; generating a set of phase current commands from the instantaneous rotor angle and from a torque reference signal, each of the phase current commands comprising at least one ripple compensation command segment and at least one zero current command segment; and converting the set of phase current commands to a set of current reference signals.
25 Citations
15 Claims
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1. A method for shaping current in an electronically commutated motor (ECM) comprising:
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acquiring a set of terminal voltage measurements;
estimating an instantaneous rotor angle from said terminal voltage measurements;
generating a set of phase current commands from said instantaneous rotor angle and from a torque reference signal, each of said phase current commands comprising at least one ripple compensation command segment and at least one zero current command segment; and
converting said set of phase current commands to a set of current reference signals. - View Dependent Claims (2, 3, 4)
maintaining a timer having an instantaneous timer value;
evaluating said angle estimation function at said instantaneous timer value to yield said instantaneous rotor angle;
including said instantaneous timer value in a set of recorded timer values whenever any of said terminal voltage measurements crosses a voltage threshold; and
constructing an angle estimation function from said set of recorded timer values and from a set of respective, pre-stored rotor angles.
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3. The method of claim 1 wherein generating said set of phase current commands from said instantaneous rotor angle and from said torque reference signal comprises:
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generating a set of unit six-step commands from said instantaneous rotor angle;
multiplying said set of unit six-step commands by said torque reference signal to yield a set of scaled six-step commands;
computing a set of ripple compensation command segments from said instantaneous rotor angle and said torque reference signal; and
adding said scaled six-step commands to respective ones of said ripple compensation command segments to yield said phase current commands.
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4. The method of claim 3 further comprising maintaining a timer having an instantaneous timer value and wherein said set of ripple compensation command segments are also functions of said instantaneous timer value.
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5. An apparatus for shaping current in an electronically commutated motor (ECM) comprising:
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an ECM interface adapted to acquire a set of terminal voltage measurements;
a rotor angle estimator adapted to compute an instantaneous rotor angle from said terminal voltage measurements;
a current command generator adapted to compute a set of phase current commands from said instantaneous rotor angle and from a torque reference signal, each of said phase current commands comprising at least one ripple compensation command segment and at least one zero current command segment; and
a current controller interface adapted to convert said set of phase current commands to a set of current reference signals. - View Dependent Claims (6, 7, 8)
a timer adapted to maintain an instantaneous timer value;
a function evaluator adapted to evaluate an angle estimation function at said instantaneous timer value to yield said instantaneous rotor angle;
an event recorder adapted to include said instantaneous timer value in a set of recorded timer values whenever any of said terminal voltage measurements crosses a voltage threshold; and
a function constructor adapted to construct said angle estimation function from said set of recorded timer values and from a set of respective, pre-stored rotor angles.
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7. The apparatus of claim 5 wherein said current command generator further comprises:
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a unit six-step command generator adapted to generate a set of unit six-step commands from said instantaneous rotor angle;
a multiplier adapted to multiply said set of unit six-step commands by said torque reference signal to yield a set of scaled six-step commands;
a command segment generator adapted to compute a set of ripple compensation command segments from said instantaneous rotor angle and said torque reference signal; and
an adder adapted to add said scaled six-step commands to respective ones of said ripple compensation command segments to yield said phase current commands.
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8. The apparat us of claim 7 further comprising a timer adapted to maintain an instantaneous timer value and wherein said command segment generator is further adapted to receive said instantaneous timer value.
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9. An apparatus for shaping current in an electronically commutated motor (ECM) comprising:
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an analog-to-digital converter adapted to acquire a set of terminal voltage measurements;
a current controller interface adapted to convert a set of phase current commands to a set of current reference signals; and
a digital signal processor adapted to implement an algorithm comprising;
estimating an instantaneous rotor angle from said terminal voltage measurements; and
generating said set of phase current commands from said instantaneous rotor angle and from a torque reference signal, each of said phase current commands comprising at least one ripple compensation command segment and at least one zero current command segment. - View Dependent Claims (10, 11, 12)
maintaining a timer having an instantaneous timer value;
evaluating an angle estimation function at said instantaneous timer value to yield said instantaneous rotor angle;
including said instantaneous timer value in a set of recorded timer values whenever any of said terminal voltage measurements crosses a voltage threshold; and
constructing said angle estimation function from said set of recorded timer values and from a set of respective, pre-stored rotor angles.
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11. The apparatus of claim 9 wherein generating said set of phase current commands from said instantaneous rotor angle and from a torque reference signal comprises:
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generating a set of unit six-step commands from said instantaneous rotor angle;
multiplying said set of unit six-step commands by said torque reference signal to yield a set of scaled six-step commands;
computing a set of ripple compensation command segments from said instantaneous rotor angle and said torque reference signal; and
adding said scaled six-step commands to respective ones of said ripple compensation command segments to yield said phase current commands.
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12. The apparatus of claim 11 wherein generating said set of phase current commands further comprises maintaining a timer having an instantaneous timer value and wherein said set of ripple compensation command segments are also functions of said instantaneous timer value.
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13. A method for shaping current in an electronically commutated motor (ECM) comprising:
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acquiring a set of terminal voltage measurements;
maintaining a timer having an instantaneous timer value;
evaluating an angle estimation function at said instantaneous timer value to yield an instantaneous rotor angle;
including said instantaneous timer value in a set of recorded timer values whenever any of said terminal voltage measurements crosses a voltage threshold;
constructing said angle estimation function from said set of recorded timer values and from a set of respective, pre-stored rotor angles;
generating a set of unit six-step commands from said instantaneous rotor angle;
multiplying said set of unit six-step commands by said torque reference signal to yield a set of scaled six-step commands;
computing a set of ripple compensation command segments from said instantaneous rotor angle, said torque reference signal, and said instantaneous timer value;
adding said scaled six-step commands to respective ones of said ripple compensation command segments to yield said phase current commands; and
converting said set of phase current commands to a set of current reference signals.
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14. An apparatus for shaping current in an electronically commutated motor (ECM) comprising:
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an analog-to-digital converter adapted to acquire a set of terminal voltage measurements;
a current controller interface adapted to convert a set of phase current commands to a set of current reference signals; and
a digital signal processor adapted to implement an algorithm comprising;
maintaining a timer having an instantaneous timer value;
evaluating an angle estimation function at said instantaneous timer value to yield an instantaneous rotor angle;
including said instantaneous timer value in a set of recorded timer values whenever any of said terminal voltage measurements crosses a voltage threshold;
constructing said angle estimation function from said set of recorded timer values and from a set of respective, pre-stored rotor angles;
generating a set of unit six-step commands from said instantaneous rotor angle;
multiplying said set of unit six-step commands by said torque reference signal to yield a set of scaled six-step commands;
computing a set of ripple compensation command segments from said instantaneous rotor angle, said torque reference signal, and said instantaneous timer value; and
adding said scaled six-step commands to respective ones of said ripple compensation command segments to yield said phase current commands.
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15. An apparatus for shaping current in an electronically commutated motor (ECM) comprising:
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an electronic threshold crossing detector adapted to generate a threshold crossing signal whenever any ECM terminal voltage crosses a voltage threshold;
a current controller interface adapted to convert a set of phase current commands to a set of current reference signals; and
a digital signal processor adapted to implement an algorithm comprising;
maintaining a timer having an instantaneous timer value;
evaluating an angle estimation function at said instantaneous timer value to yield an instantaneous rotor angle;
including said instantaneous timer value in a set of recorded timer values in response to said threshold crossing signal;
constructing said angle estimation function from said set of recorded timer values and from a set of respective, pre-stored rotor angles;
generating a set of unit six-step commands from said instantaneous rotor angle;
multiplying said set of unit six-step commands by said torque reference signal to yield a set of scaled six-step commands;
computing a set of ripple compensation command segments from said instantaneous rotor angle, said torque reference signal, and said instantaneous timer value; and
adding said scaled six-step commands to respective ones of said ripple compensation command segments to yield said phase current commands.
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Specification