# US 5,349,276 A · Control system for regulating motor speed > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,349,276 A - Document ID: US5349276A - Status: Granted - Kind: A - Application number: 08/054,541 - Filed: 1993-04-27 - Granted: 1994-09-20 - Earliest claimed: 1992-02-28 - Assignees: The Walt Disney Company - Inventors: Frank Mezzatesta, Jr.; Donald M. Young - Web page: https://patentgrep.com/patent/US5349276A ## CPC - H02H 7/093: against increase beyond, or decrease below, a predetermined level of rotational speed (centrifugal switches H01H35/10) - B60L 3/0023: {Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train} - B60L 53/24: Using the vehicle's propulsion converter for charging - G01P 3/48: by measuring frequency of generated current or voltage {(in general G01R23/00)} - Y02T 10/70: Energy storage systems for electromobility, e.g. batteries - Y02T 10/7072: Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors - Y02T 90/12: Electric charging stations - Y02T 90/14: Plug-in electric vehicles - Y10S 388/903: Protective, e.g. voltage or current limit - Y10S 388/909: Monitoring means - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A motor control system accurately and reliably controls the speed of a motor so that the motor operates in accordance with a predetermined motor speed profile, and therefore does not exceed a predetermined safe speed, decelerates at a controlled rate, maintains a safe minimum speed, and does not turn in reverse. If the motor operates out of these limits, a malfunction is indicated and the control system halts operation of the motor. The motor speed is determined using an electronic tachometer that analyzes the current in at least two phases of the motor to provide extremely precise and reliable velocity information for the motor. ## Claims ### Claim 1 A control system for regulating the speed of a motor having a rotatable rotor and windings that define poles of the motor, the control system comprising: a variable frequency drive that produces a drive signal that is provided to the windings of the motor to cause rotation of the rotor; speed means for providing a speed signal that indicates the actual speed of the rotor; monitor means for receiving the speed signal and generating monitor signals that indicate motor performance relative to a speed profile of desired :motor speed during operation of the motor; and control means for receiving the monitor signals and comparing the monitor signals with predetermined expected values, and for indicating a failure condition if an unexpected value is obtained and if the unexpected value persists for greater than a predetermined time interval. ### Claim 2 (depends on 1) A control system as defined in claim 1, wherein the monitor means generates monitor signals that indicate when the speed of the motor exceeds a minimum full speed, when the actual speed of the motor is below a maximum slow speed, and when the motor is properly decelerating. ### Claim 3 (depends on 1) A control system as defined in claim 1, wherein the control means generates command signals in response to the motor speed profile and the monitor signals, and wherein the command signals are provided to the variable frequency drive and determine the drive signal generated by the variable frequency drive. ### Claim 4 (depends on 3) A control system as defined in claim 3, wherein the control means restarts a timer count for an unexpected signal combination whenever the signal combination assumes an unexpected value. ### Claim 5 (depends on 4) A control system as defined in claim 4, wherein the monitor means generates monitor signals that indicate when the motor is exceeding a minimum full speed, when the motor is below a maximum slow speed, and when the motor is properly decelerating. ### Claim 6 (depends on 1) A control system as defined in claim 1, further including a contactor switch that connects and disconnects the motor from the drive signals produced by the variable frequency drive. ### Claim 7 (depends on 6) A control system as defined in claim 6, wherein the control means generates command signals in response to the motor speed profile and the monitor signals, and wherein the variable frequency drive receives the command signals and in response generates the drive signals, and the contactor switch receives the command signals and in response opens and closes. ### Claim 8 (depends on 7) A control system as defined in claim 7, wherein the monitor means generates monitor signals that indicate when the speed of the motor exceeds a minimum full speed, when the speed of the motor is below a maximum slow speed, and when the speed of the motor is within a decreasing ramp speed interval. ### Claim 9 (depends on 8) A control system as defined in claim 8, wherein the monitor means generates monitor signals comprising: a Ramping-Down-or-Stopped monitor signal that has a high value when the motor speed is within a decreasing ramp speed interval or when the motor speed is less than a maximum low speed, and has a low value otherwise; a Full-Speed monitor signal that has a high value when the motor speed is greater than a minimum Full-Speed and has a low value otherwise; and a Forward/Normal-Speed monitor signal that has a high value when the motor speed is greater than the maximum low speed value and is less than a maximum full speed value. ### Claim 10 (depends on 9) A control system as defined in claim 9, wherein the control means generates command signals that comprise: a Motor Run command signal that commands the variable frequency drive to generate motor drive signals; a Full-Speed command signal that is high when the control means determines that the motor should be driven at its full speed and has a low value when the control means determines that the motor should be driven at an intermittent speed; an Emergency Stop command signal that has a low value when the control means determines that the motor should be halted immediately, and has a high value when the control means determines that the motor should be provided with drive signals; and a Power-Disconnect command signal that is high when the control means determines that the motor should be provided with drive signals. ### Claim 11 (depends on 10) A control system as defined in claim 10, wherein the control means indicates a plurality of failure modes that comprise: a Motor-Failed-to-Run failure mode that is indicated if the Motor Run command signal has a low value and Contactor monitor signal has a high value and if this combination persists for greater than a predetermined time interval; a Motor-Failed-to-Stop failure mode that is indicated if the Motor Run command signal has a high value and the contactor monitor signal has a low value, and if this combination persists for greater than a predetermined time interval; a Motor-Failed-to-Run failure mode that is indicated if the Motor Run command signal has a low value, the Full-Speed command signal has a low value, and the Forward/Normal-Speed monitor signal has a high value, and if this combination persists for greater than a predetermined time interval; a Motor-Failed-to-Run-Full-Speed failure mode that is indicated if the Motor Run command signal has a low value, the Full-Speed command signal has a low value, and the Full-Speed monitor signal has a high value, and if this combination persists for greater than the time ordinarily necessary for the motor to reach full speed from a stopped condition; a Motor-Running-in-Reverse failure mode that is indicated if the Ramping-Down-or-Stopped monitor signal has a high value, the Full-Speed monitor signal has a high value, and the Forward/Normal-Speed monitor signal has a high value, and if this combination persists for greater than a predetermined input update time for the control means; a Motor-Running-Overspeed failure mode that is indicated if the Full-Speed monitor signal has a low value and the Forward/Normal-Speed monitor signal has a high value, and if this condition persists for greater than an input update time interval for the control means; a Motor-Failed-to-Decelerate failure mode that is indicated if the Motor Run command signal has a low value, the Full-Speed command signal has a high value, and the Ramping-Down-or-Stopped monitor signal has a high value, and if this combination of values persists for a time interval greater than is necessary for the speed means to indicate a reduction in motor speed from its full speed to its low speed; a Motor-Failed-to-Stop failure mode that is indicated if the Motor Run command signal is high and the Forward/Normal-Speed monitor signal is low, and if this combination of values persists for greater than a predetermined time interval in which the motor ordinarily can decrease from its full speed to its low speed; and a Motor-Failed-to-Accelerate failure mode that is indicated if the Motor Run command signal is low, the Full-Speed command signal is low, and the Ramping-Down-or-Stopped monitor signal is low, and if this combination of values persists for a time interval greater than the time it ordinarily takes for the motor to ramp up to full speed. ### Claim 12 (depends on 1) A control system as defined in claim 1, wherein the speed means comprises an electronic tachometer including: signal means for producing a current signal that corresponds to the current in at least one pole of the motor; filter means for removing frequency components of the current signal greater than a predetermined maximum value of the motor speed profile to provide a filtered signal; and pulse means for providing a pulse signal that indicates the frequency of the filtered signal. ### Claim 13 (depends on 12) A control system as defined in claim 12, wherein the filter means comprises a low-pass filter that filters out frequency components greater than approximately 75 Hz. ### Claim 14 (depends on 13) A control system as defined in claim 13, wherein the low-pass filter includes resistive and capacitive elements coupled to an amplifier element. ### Claim 15 (depends on 12) A control system as defined in claim 12, wherein the pulse means comprises a zero-crossing detector that produces a transition at each zero-crossing of the filtered signal. ### Claim 16 (depends on 15) A control system as defined in claim 15, wherein the zero-crossing detector comprises a resistive element coupled to an operational amplifier. ### Claim 17 (depends on 12) A control system as defined in claim 12, wherein the signal means comprises a current sensor that is coupled to one pole of the motor. ### Claim 18 A control system for regulating the speed of a motor, comprising: an electronic tachometer coupled to the motor, said electronic tachometer producing a tachometer output that represents the speed of the motor; a monitor that receives said tachometer output and stores in memory a motor speed profile that represents desired motor speed during operation of the motor, said monitor comparing said tachometer output with said motor speed profile, and producing an error signal if a difference between said tachometer output and said motor speed profile exceeds predetermined expected values; and, a timer coupled to receive said error signal and that indicates a failure condition if an unexpected value is obtained and persists for greater than a predetermined time interval. ### Claim 19 (depends on 18) A control system according to claim 18, wherein: the motor has a rotor that rotates relative to windings that define poles of the motor; said electronic tachometer includes a detector coupled to one of the windings so as to produce a varying electronic signal representative of the motor's phase, and, a pulse circuit that is coupled to said detector to receive said varying electronic signal and that produces said tachometer output as a pulsed output signal having a first state when said varying electronic signal matches a predefined one of a voltage and current level and a different state when said varying electronic signal does not match said predefined one; said monitor determines the speed of the motor in dependence upon the frequency with which said tachometer output has said first state. ### Claim 20 A control system for regulating the speed of a motor having a rotatable rotor and windings that define poles of the motor, said control system comprising: a variable frequency drive that produces a drive signal that is provided to the windings of the motor to cause rotation of the motor; a computer that controls operation of said variable frequency drive to run, accelerate, decelerate the motor within a predetermined motor speed profile; an electronic tachometer that electronically taps at least two windings of the motor and that produces at least one pulsed output signal that represents change of polarity of current of a phase of the motor and at least one output signal that indicates direction of rotation of the rotor; and control logic, coupled to receive said output signals from said electronic tachometer, that stores in memory a motor speed profile that represents desired motor speed during operation of the motor, including error bounds for each of desired acceleration and deceleration, compares motor speed to said motor speed profile that represents desired motor speed during operation of the motor, produces an error signal if a difference between said tachometer output and said motor speed profile exceeds said error bounds, and, indicates a failure condition an unexpected value is obtained and persists greater than a predetermined time interval.