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US 8,138,708 B2Granted
Closed-loop motor driver compensation
AssigneeAllegro MicroSystems, LLC
InventorsMichael G. Ward, David J. Haas
Life of this patent
Estimating the term…
Abstract
A control loop circuit for use in a closed-loop control system that controls a system such as a linear motor is presented. The control loop circuit includes a lead-lag compensator that features a lead compensation network configured to reduce output noise without substantially changing the effect of the lead compensation in the control system's frequency response.
Claims35
A circuit comprising:
- an error amplifier having a first input to receive a reference signal, a second input and an output to produce an error signal based on the first input and the second input;
- a lead-lag compensator comprising a lead portion and a lag portion, the lead portion being connected between the second input of the error amplifier and a feedback path from an external controlled system of a closed-loop control system having an associated frequency response, and the lag portion being connected between the second input and the output of the error amplifier;
- and
- wherein the lead portion comprises a network of passive elements connected to provide a high frequency zero for lead compensation and a high frequency pole to reduce the effect of the high frequency zero on the frequency response;
- wherein the lead portion comprises a first resistor, a second resistor and a capacitor, the second resistor and the capacitor being connected in series as a series resistive-capacitive (RC) circuit, and the first resistor being connected in parallel with the series RC circuit to form a parallel RC circuit;
- wherein the lead portion further comprises a third resistor connected in series between the parallel RC circuit and the second input of the error amplifier.
3 more elements
A device comprising:
- a driver to drive a movement by a motion device;
- a sensor to detect the movement and to produce an output in response thereto;
- a control loop circuit coupled between the sensor and the driver, the control loop circuit configured to receive as inputs the sensor output and an input provided by an external controller, and to produce an output signal based on the received inputs as an input to the driver;
- and
- wherein the control loop circuit comprises:
- an error amplifier having a first input to receive the external controller input as a reference signal, a second input and an output to produce an error signal based on the first input and the second input;
- a lead-lag compensator comprising a lead portion and a lag portion, the lead portion being connected between the second input of the error amplifier and the sensor output, and the lag portion being connected between the second input and the output of the error amplifier;
- and
- wherein the lead portion comprises a network of passive elements connected to provide a high frequency zero for lead compensation and a high frequency pole;
- wherein the lead portion comprises a first resistor, a second resistor and a capacitor, the second resistor and the capacitor being connected in series as a series resistive-capacitive (RC) circuit, and the first resistor being connected in parallel with the series RC circuit to form a parallel RC circuit;
- wherein the lead portion further comprises a third resistor connected in series between the parallel RC circuit and the second input of the error amplifier.
8 more elements
A system comprising:
- a controller;
- and
- a linear motion control device, coupled to the controller, comprising:
- a coil driver to drive a coil that, when driven, effects a linear movement by a motion device having a magnet;
- a magnetic field sensor to detect a magnetic field associated with the linear movement and to produce an output in response thereto;
- a control loop circuit coupled between the magnetic field sensor and the coil driver, the control loop circuit configured to receive as inputs the magnetic field sensor output and an input provided by the controller, and to produce an output signal based on the received inputs as an input to the coil driver;
- and
- wherein the control loop circuit comprises:
- an error amplifier having a first input to receive the controller input as a reference signal, a second input and an output to produce an error signal based on the first input and the second input;
- a lead-lag compensator comprising a lead portion and a lag portion, the lead portion being connected between the second input of the error amplifier and magnetic field sensor output, and the lag portion being connected between the second input and the output of the error amplifier;
- and
- wherein the lead portion comprises a network of passive elements connected to provide a high frequency zero for lead compensation and a high frequency pole;
- wherein the lead portion comprises a first resistor, a second resistor and a capacitor, the second resistor and the capacitor being connected in series as a series resistive-capacitive (RC) circuit, and the first resistor being connected in parallel with the series RC circuit to form a parallel RC circuit;
- wherein the lead portion further comprises a third resistor connected in series between the parallel RC circuit and the second input of the error amplifier.
11 more elements
Dependencies are inferred from the claim text.