Stepper motor control
AssigneeAnalog Devices International Unlimited Company
InventorThomas Ernst
Life of this patent
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Abstract
A new method and circuit arrangement for operating a stepper motor in a voltage-based operating mode with a control loop over the whole operating range of speeds of a stepper motor. The method/circuit arrangement includes calculating a load angle of the stepper motor. The load angle is then used to calculate a voltage-based control signal suitable for operating a known motor driver circuit, such as a chopper, to drive the stepper motor coils. This enables improved control over the stepper motor which can improve control stability.
Claims20
A circuit arrangement for operating a stepper motor, the circuit arrangement comprising:
- a micro-step sequencer configured to:
- store micro-step values associated with discrete values of a quantised waveform, and
- output:
- a first micro-step value associated with a first phase angle position of the quantised waveform, and a second micro-step value associated with a second phase angle position of the quantised waveform;
- a register configured to store a fractional value, wherein the fractional value represents a fraction between the first micro-step value and the second micro-step value;
- and
- an interpolator configured to:
- receive the first micro-step value, the second micro-step value, and the fractional value,
- interpolate, between the first micro-step value and the second micro-step value, based on the fractional value, and
- determine a fractional micro-step value from the interpolation;
- and
- wherein the circuit arrangement is configured to operate the stepper motor based on the fractional micro-step value.
A method for determining a target current of a motor coil of a stepper motor, the method comprising:
- providing a quantised waveform representing micro-stepped current;
- generating a first micro-step value associated with a first phase angle position of the quantised waveform;
- generating a second micro-step value associated with a second phase angle position of the quantised waveform;
- providing a fractional value representing a fraction between the first micro-step value and the second micro-step value;
- interpolating, between the first micro-step value and the second micro-step value, based on the fractional value, to generate a fractional micro-step value;
- and
- generating a target current value based on the fractional micro-step value, wherein the target current value is suitable for operating the stepper motor.
A method for determining a target current of a motor coil of a stepper motor, the method comprising:
- providing, by a micro-step sequencer, a quantised waveform representing micro-stepped current;
- generating, by the micro-step sequencer, a first micro-step value associated with a first phase angle position of the quantised waveform;
- generating, by the micro-step sequencer, a second micro-step value associated with a second phase angle position of the quantised waveform;
- providing, by a register, a fractional value representing a fraction between the first micro-step value and the second micro-step value;
- interpolating, by an interpolator, between the first micro-step value and the second micro-step value, wherein interpolating is based on generating a fractional micro-step value base on the fractional value;
- and
- generating a target current value based on the fractional micro-step value, wherein the target current value is suitable for operating the stepper motor.
Dependencies are inferred from the claim text.