Brushless motor speed control

Claim 2

A digital speed control circuit for an electric motor having a phase winding which is selectively energized to apply force to a rotor comprising: delay means (70) for providing a delay interval; and on-time means (60) for providing an on-time interval during which a phase winding should be energized; characterized by: means (30, 40, 50) for receiving an input signal indicative of the rotor position; logic means (34, 44, 54) for generating a driver signal to cause said phase winding to be energized, said logic means acting to initiate the delay means to provide the delay interval upon the receipt of the input signal and to initiate the on-time means after the delay interval has elapsed, said logic means further acting to generate said drive signal for the duration of the on-time interval, the durations of delay interval and of the on-time being independent.

Claim 3

The control circuit as set forth in claim 1 wherein the delay means (70) further comprises a delay counter (160), a delay time register (160) connected to the delay counter for latching a value into the delay counter and clock means (30, 32) for indexing said delay counter to provide the delay interval.

Claim 4

The control circuit as set forth in claim 2 wherein the on-time means further comprises an on-time counter (150), an on-time register (150) connected to the on-time counter for latching a value into the on-time counter and means (150) for receiving a clock signal to index said on-time counter to provide the on-time interval.

Claim 5

The control circuit as set forth in claim 3 further comprising: timing data input means (114) connected to provide selected values to the delay time register and the on-time register.

Claim 6

The control circuit as set forth in claim 3 wherein the delay time register and the on-time register comprise: input means (110, 112) to increment or decrement the registers.

Claim 7

The control circuit as set forth in claim 5 wherein the delay time register and the on-time register further comprise: control means (152, 154, 156-159, 162, 164, 166-169) for preventing the registers from "rolling over".

Claim 8

The control circuit as set forth in claim 1 wherein the means (30, 40, 50) for receiving an input signal comprises a Hall effect sensor positioned to generate a signal when the application of current to the phase winding is capable of producing a positive torque upon the rotor.

Claim 9

The control circuit as set forth in claim 1 wherein the electric motor has multiple windings and which comprises means (30, 40, 50) for receiving an input signal, delay means (70), on-time means (60) and logic means (34, 44, 54) for each winding.

Claim 10

The control circuit as set forth in any one of the claims 1 to 8 which comprises: said logic means having a phase timing circuit (34) that receives a signal (31) from a rotor position detecting means, a signal (33) from a frequency multiplier (32) circuit and signals from the delay means and on-time means and generates an output signal based on the values of the received signals; and a driver circuit (36, 46, 56) for each phase winding of the motor that receives the output signal from the phase timing circuit and which supplies a pulse of current to the motor winding at optimum position of a rotor within the motor to produce maximum torque and for a duration to sustain a preselected rotor speed.

Claim 11

The control circuit as set forth in claim 9 wherein said delay time counter (160) is clocked at the rate determined by the frequency multiplier (32) to determine the delay interval between the receipt of a signal from the rotor position detecting means (30,40,50 and the generation of an output signal.

Claim 12

The control circuit as set forth in claim 10 wherein the phase timing circuit further comprises an on-time counter (150) which is clocked at a rate determined by the frequency multiplier (32) after the delay interval has elapsed, the output signal indicating to the driver circuit to supply power to the winding during the interval the on-time counter is counting.

Claim 13

An electronically controlled motor including a rotor supported for rotational movement and a motor field (102) which comprises: a rotor position detection means (30,40,50) for generating a position signal and a driver circuit (36,46,56) for each winding of the motor, said circuit receiving a driver signal and supplying a pulse of current to said winding for the duration of said driver signal; characterized by said rotor position detection means generating said position signal when the rotor is positioned relative to a winding such that the application of current to the winding will result in positive torque being applied to the rotor; and logic means (34,44,54) connected to receive the position signal and to generate a driver signal, said logic means including delay means (70) for determining a delay interval between the receipt of the position signal and the generation of the driver signal and on-time means (60) for determining the duration of the driver signal, the durations of the delay interval and of the on-time being independent.

Claim 14

An electronically controlled motor including a rotor supported for rotational movement and a motor field (102) which comprises: a rotor position detection means (30,40,50) for generating a position signal and a driver circuit (36,46,56) for each winding of the motor, said circuit receiving a driver signal and supplying a pulse of current to said winding for the duration of said driver signal; characterized by said rotor position detection means generating said position signal when the rotor is positioned relative to a winding such that the application of current to the winding will result in positive torque being applied to the rotor; and logic means (34,44,54) connected to receive the position signal and to generate a driver signal, said logic means including delay means (70) for determining a delay interval between the receipt of the position signal and the generation of the driver signal and on-time means (60) for determining the duration of the driver signal, the durations of the delay interval and of the on-time being independent.

Claim 15

The motor as set forth in claim 12 wherein the delay means comprises a delay register (160) containing preset values and a delay counter (160), said delay counter counting from the delay register value at a known rate to determine the delay interval.

Claim 16

The motor as set forth in claim 13 wherein the delay counter (160) is connected to the delay register (160) such that the delay counter receives a value equal to approximately one-half the value in the delay register.

Claim 17

The motor as set forth in claim 14 wherein the on-time means (60) comprises an on-time register (150) containing preset values and an on-time counter (150), said counter being indexed from the on-time register value at a known rate to determine the on-time interval.

Claim 20

The method as set forth in claim 16 wherein the steps of determining the delay interval and determining the on-time interval act in combination to provide the driver signal during that portion of the rotation of the rotor when the torque is maximized for the current supplied to the winding.

Claim 21

The method as set forth in claim 16 wherein the steps of determining the delay interval and of determining the on-time interval act to control rotor speed.

Claim 22

The method as set forth in claim 16 wherein the steps of determining the delay interval and determining the on-time interval comprise establishing delay intervals in a digital circuit.