Motor controller with power limiting

Claim 2

In proportional speed controlling, electric motor-driving apparatus which produces a speed control signal and responds thereto normally to apply electrical power to a motor for a portion of each of a succession of periodic times, the improvement comprising A. means for producing a first signal responsive to the speed of the motor, B. means for producing a reference signal proportional to a selected maximum electrical voltage available for application to such motor at the instantaneous speed of the motor, C. reference feedback means connected to said reference producing means for producing a second signal responsive to said reference signal, D. compare means for producing a third signal responsive to a comparison of said first signal with said second signal, and E. gating means for producing an inhibit signal having in each of said periodic times an inhibit interval responsive in duration to said third signal, and for disabling said response to said speed control signal for said inhibit interval in each said periodic time.

Claim 3

In speed controlling apparatus as defined in claim 1, the further improvement in which said reference feedback means includes means for producing said second signal to identify a limited maximum starting voltage available to the motor and to identify a limited acceleration voltage available to the motor.

Claim 4

In speed controlling apparatus as defined in claim 1, the further improvement comprising offset means in said reference feedback means for applying a selected offset component to said second signal.

Claim 5

In speed controlling apparatus as defined in claim 1 the further improvement comprising rate means in said reference feedback means for producing said second signal in response to a selected portion of said maximum electrical voltage available for application to said motor.

Claim 6

In speed controlling apparatus as defined in claim 1, the further improvement comprising delay means in circuit with said first signal-producing means and responding to a rising-speed condition of said first signal to introduce a time delay between the value of the actual speed of the motor and the speed-responsive value of said first signal.

Claim 7

In speed controlling apparatus as defined in claim 1, the further improvement comprising limit means in circuit with said first signal-producing means for limiting the maximum value of said first signal.

Claim 8

In phase-controlled electric motor drive apparatus having a motor-driving circuit for selectively gating rectified periodically-alternating voltage to the motor in response to the actual motor speed relative to a selected motor speed, the improvement comprising A. a reference load resistor, B. reference drive means for applying to said load resistor phase-controlled electrical voltage in synchronism with said rectified alternating voltage, C. adjustable timing means connected with said motor driving circuit for limiting the maximum phase duration of said gated voltage applied to the motor and connected with said reference drive means for actuating said reference drive means to apply said phase controlled voltage to said reference resistor for said maximum phase duration, and D. feedback controlling means for adjusting said maximum phase duration of said timing means in response to a comparison of a reference signal identifying the electrical power said drive means applies to said reference resistor and a speed signal identifying said actual motor speed.

Claim 9

In phase-controlled electric motor drive apparatus having a motor-driving circuit for selectively gating rectified periodically-alternating voltage to the motor in response to the actual motor speed relative to a selected motor speed, the improvement comprising A. a reference load resistor, B. reference drive means for applying to said load resistor phase-controlled electrical voltage in synchronism with said rectified alternating voltage, C. adjustable timing means connected with said motor driving circuit for limiting the maximum phase duration of said gated voltage applied to the motor and connected with said reference drive means for actuating said reference drive means to apply said phase controlled voltage to said reference resistor for said maximum phase duration, and D. feedback controlling means for adjusting said maximum phase duration of said timing means in response to a comparison of a reference signal identifying the electrical power said drive means applies to said reference resistor and a speed signal identifying said actual motor speed.

Claim 10

In drive apparatus as defined in claim 7, the further improvement in which said feedback controlling means increases said maximum phase duration with increasing motor speed, and includes acceleration-limiting means for limiting the rate at which it increases said maximum phase duration with increasing motor speed.

Claim 11

In drive apparatus as defined in claim 8, the further improvement comprising means for limiting the value of said maximum phase duration independent of actual motor speed in excess of a selected value.

Claim 12

In drive apparatus as defined in claim 7, the further improvement in which said acceleration-limiting means includes A. rate means connected with said feedback controlling means for selectively proportioning said reference signal to adjust the portion of said reference load power compared with said motor speed signal, and B. delay means connected with said feedback controlling means and introducing a selected delay in said speed signal relative to the actual motor speed.

Claim 13

Electrical drive apparatus for connection to an electrical motor and comprising A. an adjustable trigger generator for the phase-controlled gating of rectified alternating supply voltage to such motor in response to a difference function between a speed sigNal identifying and responsive to the motor speed and a further signal identifying a selected motor speed, B. gating means connected with said trigger generator, synchronized with said alternating supply voltage, and responsive to a limit error signal to produce an inhibit signal for enabling said trigger generator to gate said supply voltage to such motor only after an inhibit time in each half cycle of said alternating voltage, C. reference means synchronized with said alternating supply voltage and connected with said gating means for producing a reference signal responsive to the magnitude of the maximum limit of alternating supply voltage said gating means enables said trigger generator to apply to such motor, and D. feedback means producing said limit error signal in response to an arithmetic difference function of said reference signal relative to said speed signal.

Claim 14

Electrical drive apparatus for connection to an electrical motor and comprising A. an adjustable trigger generator for the phase-controlled gating of rectified alternating supply voltage to such motor in response to a difference function between a speed sigNal identifying and responsive to the motor speed and a further signal identifying a selected motor speed, B. gating means connected with said trigger generator, synchronized with said alternating supply voltage, and responsive to a limit error signal to produce an inhibit signal for enabling said trigger generator to gate said supply voltage to such motor only after an inhibit time in each half cycle of said alternating voltage, C. reference means synchronized with said alternating supply voltage and connected with said gating means for producing a reference signal responsive to the magnitude of the maximum limit of alternating supply voltage said gating means enables said trigger generator to apply to such motor, and D. feedback means producing said limit error signal in response to an arithmetic difference function of said reference signal relative to said speed signal.

Claim 15

Motor driving apparatus as defined in claim 11 A. in which said alternating supply voltage has a periodic waveform, and B. further comprising synchronizing means in circuit with said alternating supply voltage and applying to each of said gating means, said reference means, and said trigger generator a synchronizing signal having a pulse coincident with each zero-voltage crossing of said supply voltage.

Claim 16

Motor driving apparatus as defined in claim 11 in which said reference means further comprises A. a reference resistor, B. a reference trigger generator responsive to said inhibit signal for gating said alternating supply voltage to said reference resistor upon termination of each inhibit time, and C. sensor means coupled with said reference resistor for producing said reference signal in response to the voltage said reference trigger generator applies to said reference resistor.

Claim 17

Motor driving apparatus as defined in claim 11 A. in which said supply voltage has a periodic waveform, and B. in which said gating means produces said inhibit signal in each half cycle of said supply voltage commencing with each zero-crossing thereof and with a duration less than half the period thereof, thereby to limit the maximum voltage said adjustable trigger generator applies to such motor.

Claim 18

Motor driving apparatus as defined in claim 11 in which said feedback means includes A. differential amplifier means producing said limit error signal and having two inputs, one of which receives said reference signal, and B. delay integrator means receiving said speed signal and applying it to the other input of said differential amplifier with a first delay when said speed signal identifies an increasing motor speed, and otherwise with lesser delay.

Claim 19

Motor driving apparatus as defined in claim 15 in which feedback means includes limit-clamping means connected with said other input of said differential amplifier and for limiting the value of the speed-responsive signal applied thereto.

Claim 20

Motor driving apparatus as defined in claim 11 in which said feedback means includes an offset generator for superposing said reference signal on a selected offset signal.

Claim 21

Motor driving apparatus as defined in claim 11 further comprising proportional controller means producing said speed signal with a zero-speed value in the absence of a non-zero motor speed.