BRUSHLESS D. C. MOTOR USING HALL GENERATORS FOR COMMUTATION

• US 3,783,359 A
• Filed: 12/23/1971
• Issued: 01/01/1974
• Est. Priority Date: 12/23/1971
• Status: Expired due to Term

• Current Assignee: Saul L. Malkiel
• Original Assignee: Saul L. Malkiel
• Inventors: Malkiel, Saul L.
• Primary Examiner(s): Gilheany, Bernard A.
• Assistant Examiner(s): Duncanson, Jr., W. E.
• Application Number:
  US05/211,519
• Time in Patent Office: 740 Days
• Field of Search: 318/254,439
• US Class Current: 318/400.09
• CPC Class Codes: H02P 6/24 Arrangements for stopping

Abstract

A brushless motor is driven by a transistorized bridge and commutated by an arrangement of Hall generators. The motor is controlled in torque generating and constant speed modes. Pulse width modulation is applied to control the amplitude of the motor voltage and regenerative braking is applied.

Claims

1. A brushless direct current motor including motor driving means, comprising:

first, second and third position sensors for sensing the position of the motor armature, and each of said sensors providing an alternating signal;

first, second and third trigger means connected to the first, second and third position sensors, respectively, and each of said triggers providing an alternating signal when the alternating signal from the respective position sensor is zero;

commutation circuitry connected to the first, second and third triggers and responsive to the signals therefrom for providing a plurality of commutating signals;

a power bridge connected to the commutation circuitry and responsive to the plurality of signals therefrom for driving the motor;

means responsive to a torque command signal for providing a signal corresponding to the absolute value of the signal;

a feedback circuit connected to the power bridge and responsive to signals therefrom for providing selected feedback signals;

means connected to the absolute value signal means and to the feedback circuit for combining the signals therefrom;

means connected to the combining means and responsive to the combined signal for providing a corresponding pulse output; and

the last mentioned means connected to the commutation circuit, with the pulse output affecting the commutation circuit to control the effective amplitude of the motor driving signals from the power bridge.

2. A motor as described by claim 1 including:

means responsive to the torque command signal for providing a signal at one level when the torque command signal is in one sense and for providing a signal at another level when the torque command signal is in an opposite sense;

a threshold detector connected to the combining means and responsive to the signal therefrom for providing a threshold signal;

a directional detector connected to the triggers for sensing the sense of the signals therefrom;

a power supply connected to the power bridge;

a mode selector connected to the threshold detector, the directional detector and the means for providing signals at the one and another levels, and responsive to the signals therefrom for providing mode control signals; and

the commutating circuit connected to the mode selector and responsive to the mode control signals therefrom for affecting the power bridge to control direction of current to the motor, and to control the sense of the motor speed.

3. A motor as described by claim 2, wherein:

the feedback circuit is connected to the mode selector and responsive to the signals therefrom for selectively providing a feedback signal in accordance with the direction of motor current and the sense of the motor speed

4. A motor as described by claim 1, including:

means for providing a signal at a reference frequency;

means connected to the first, second and third triggers and to the reference signal means for comparing the signals therefrom and for providing an output at a predetermined level when the frequency of one of the trigger signals is below the reference frequency; and

switching means connecting the comparing means to the combining means for stabilizing motor speed.

5. A motor as described by claim 1, wherein:

the position sensors are Hall Generators spaced 120 electrical degrees apart in magnetic flux sensing relation to a rotor coupled to the motor armature and rotating therewith; and

the Hall Generators provide three out-of-phase sinusoidal signals.

6. A motor as described by claim 5, wherein:

the triggers provide three square wave signals having the same phase, respectively, as the sinusoidal signals from the Hall Generators.

7. A motor as described by claim 6, wherein:

the plurality of commutation signals includes six signals, each 120* wide and overlapping by 60*.

8. A motor as described by claim 1, wherein the motor is a three wire motor;

and the bridge is a three phase bridge.

9. A motor as described by claim 1, wherein the power bridge includes:

a plurality of current flow control devices corresponding to the plurality of commutating signals, each of the current flow control devices receving one of the signals, said current flow control devices arranged in parallel pairs;

a power supply connected to at least one of the current flow control devices in each of the pairs; and

a pair of diodes arranged with each pair of current flow control devices for providing a path for motor current to flow to and from the power supply.