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US 4,447,771 AGranted
Control system for synchronous brushless motors
AssigneeKollmorgen Technologies Corporation
InventorJames S. Whited
Life of this patent
Estimating the term…
Abstract
A motor control system wherein the motor windings are energized by sinusoidal excitation currents synthesized from prerecorded sine values. The frequency of the winding excitation currents is synchronous with the rotor movement and the phase is a function of the rotor position with respect to the stator. The phase of the winding excitation is additionally controllable as a function of speed or some other adequate system parameter. It has further been found that the total operational speed range of the system is substantially increased by further adjusting and controlling the phase of the excitation currents as a function of the desired speed.
Claims18
A motor control system for a brushless DC motor comprising:
- a brushless DC motor including
- stator windings;
- a permanent magnet rotor and
- a position indicator for indicating the position of said rotor relative to said stator windings;
- excitation current generating circuit means responsive to said position indication from said position indicator and connected to provide sinusoidal excitation current to said stator windings, said sinusoidal excitation current being incrementally synthesized according to digital values;
- the frequency of said sinusoidal excitation current being controlled according to said position indication to create a rotating magnetic field synchronous with the rotation of said rotor;
- and
- torque angle control circuit means coupled to said excitation current generating circuit means to control the phase of said sinusoidal excitation current to dynamically control the angle between said rotating magnetic field created by said stator winding and the rotor position.
5 more elements
A motor control system for a brushless DC motor comprising;
- a brushless DC motor including stator windings;
- a permanent magnet rotor and a position indicator for indicating the position of said rotor relative to said stator windings;
- excitation current generating circuit means responsive to said position indication from said position indicator and connected to provide sinusoidal excitation current to said stator windings, the frequency of said sinusoidal excitation current being controlled according to said position indication to create a rotating magnetic field synchronous with the rotation of said rotor;
- torque angle control circuit means coupled to said excitation current generating circuit means to control the phase of said sinusoidal excitation current to dynamically control the angle between said rotating magnetic field created by said stator winding and the rotor position;
- speed sensing means coupled to said rotor to provide an indication of rotor speed and, wherein said speed sensing means is coupled to said torque angle control circuit means so that said phase of said sinusoidal excitation current varies as a function of rotor speed;
- and
- wherein said torque angle control circuit includes a read-only-memory having torque angle factors pre-recorded therein, wherein said speed sensing means provides digital speed indications used as addresses for said read-only-memory to select appropriate torque angle factors, and wherein said phase of said sinusoidal excitation current is determined by the selected torque angle factor.
4 more elements
A motor control system for a brushless DC motor comprising:
- a brushless DC motor including
- a plurality of stator windings and
- a permanent magnet rotor;
- a position indicator for providing digital indications of the rotor position;
- a speed indicator for providing digital indications of the rotor speed;
- a memory having torque angle factors recorded therein;
- means for selecting torque angle factors from said memory according to the digital indication of rotor speed and adding the selected torque angle factor to the digital indication of rotor position to derive an excitation vector position indication;
- and
- excitation current generating means for applying sinusoidal excitation currents to said windings having value proportional to sine values incrementally selected in accordance with said excitation vector position indication.
6 more elements
In a motor control system for supplying excitation current to multiple stator windings of the motor, the combination of:
- a separate read only memory for each winding, said memories having sine values recorded therein displaced from one another in accordance with the phase displacement of the motor windings;
- conversion means for providing analog voltages corresponding to the digital outputs of said memories;
- pulse width modulators connected to provide current pulses to said windings having pulse widths corresponding to analog voltage values derived from said conversion means;
- current loops for sensing the current flow to the winding and adjusting the voltages applied to said pulse width modulators so that the winding excitation currents are proportional to the analog voltages produced by said conversion means;
- and
- control circuits for providing a digital indication to said memories to indicate the desired winding excitation vector position.
3 more elements
A motor control system for a brushless DC motor comprising:
- a brushless DC motor including
- stator windings;
- a permanent magnet rotor and
- a position indicator for indicating the position of said rotor relative to said stator windings;
- excitation current generating circuit means responsive to said position indication from said position indicator and connected to provide sinusoidal excitation current to said stator windings, the frequency of said sinusoidal excitation current being controlled according to said position indication to create a rotating magnetic field synchronous with the rotation of said rotor;
- and
- torque angle control circuit means coupled to said excitation current generating circuit means to control the phase of said sinusoidal excitation current to dynamically control the angle between said rotating magnetic field created by said stator winding and the rotor position said angle between said rotating magnetic field and said rotor position being controlled according to digital torque angle factors.
4 more elements
Dependencies are inferred from the claim text.