Source: http://www.google.com/patents/US5424622?dq=7350717
Timestamp: 2017-05-28 05:31:17
Document Index: 312591914

Matched Legal Cases: ['§4', '§4', '§4', '§4', '§4', '§4', '§4', '§4', '§4', '§4', '§4', '§4', '§4', '§4', '§4', '§4']

Patent US5424622 - Dynamic brake assembly - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA method for dynamically braking a motor, the motor having a plurality of terminals and receiving an input alternating current voltage waveform, by detecting the zero crossing of the input alternating current voltage waveform and for a plurality of position of the input alternating current waveform:...http://www.google.com/patents/US5424622?utm_source=gb-gplus-sharePatent US5424622 - Dynamic brake assemblyAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS5424622 APublication typeGrantApplication numberUS 08/158,752Publication dateJun 13, 1995Filing dateNov 29, 1993Priority dateNov 29, 1993Fee statusPaidPublication number08158752, 158752, US 5424622 A, US 5424622A, US-A-5424622, US5424622 A, US5424622AInventorsKenneth Keller, Kenneth HopwoodOriginal AssigneeBaldor Electric Company, Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (11), Non-Patent Citations (25), Referenced by (21), Classifications (7), Legal Events (6) External Links: USPTO, USPTO Assignment, EspacenetDynamic brake assembly
In the art, periodic waveforms such as the one illustrated in waveform (A) of FIG. 5, although functions of time, are often referred to in terms of degrees, where 360° represents one period of the waveform. For example, when the waveform (A) in FIG. 5 is viewed in this light, the point X may be considered to occur at an angular position of 86°, while the point X' may be considered as having an angular position of 30°. In the art, the angular position at which the SCR is gated on is referred to as the "firing angle." For reasons discussed above, the value of the "firing angle" corresponds to the magnitude of the DC braking current applied to the motor.
Analog control signal AN2 is the fine braking time. By adjusting the potentiometer associated with AN2 the voltage of AN2 may be made to vary from a value of close to ground, which corresponds to a fine braking time of zero seconds, to a value close to the supply voltage, which corresponds to a fine braking time of 17 seconds. As discussed above in §4.2.2, the rough braking time is set by control signals PB7 and PC0. This rough braking time is used in conjunction with the fine braking time to determine the actual maximum braking time. In one embodiment, the master control logic sets the actual maximum braking time to the value of the rough braking time (defined by signals PB7 and PC0) plus the value of the fine braking time determined by the analog value of AN2. In this embodiment, by adjusting the rough braking time and the fine braking time signals, the actual maximum braking time may be set anywhere between 0 seconds and 62 seconds.
In addition to the control signals discussed in §§4.2.1-4.2.3 above, the dynamic brake assembly of the present invention utilizes several control signals that are derived from voltages sensed at the motor terminals. In a preferred embodiment of the present invention the sensed signals are: the ZERO CROSS signal (PB5); the SENSE signal (PB6) and the ZERO SPEED SENSE signal (AN3). The circuits for generating the sensed input signals are represented by Box 105 in FIG. 6.
Following the execution of the Initialization Routing, the Mode Select routing is executed. Basically, the Mode Select Routine reads the values of PC1 and PC2 to determine which mode setting was selected by the operator. A simple routine, such as the one illustrated in FIG. 15, performs this function and ensures a proper mode selection according to the switch settings discussed in §4.2.2 with respect to FIG. 8C.
As illustrated in FIGS. 16A-16B, the control logic for the BASIC BRAKE ROUTINE first opens the motor relay, thus cutting off the power to the motor (block 206). This is accomplished by simply setting the MOTOR CONTACT output PA7, refer to §4.2.5 above, to turn the relay off. Once the motor relay is turned off (i.e., open) the control logic then clears a flag register that, when set, indicates that the E-STOP control switch has been activated (block 207). The control logic then closes the motor contactor in the manner described above, thus allowing power to be applied to the motor (block 208).
Referring to the ZERO CROSS flow logic in FIG. 18, the manner in which a ZERO CROSS is detected will be explained. First, the control logic monitors the voltage of the ZERO CROSS input PB5, see §4.2.4 above, to determine when the voltage changes from low (e.g., negative) to high (e.g., positive) thus indicating a negative to positive transaction which is necessarily accompanied by a zero cross. (blocks 232-38). When a low to high transition is detected, the ZERO CROSS routine stores the clock value at the time the zero cross is detected (block 242) and returns to the FIRE routine (block 244). One acceptable ZERO CROSS routine may be found at lines 801-29 of the attached appendix.
Having detected the zero crossing and determining the frequency of the input the control logic executes a PRE-MAGNITUDE PROCESSING routine (block 252). The PRE-MAGNITUDE PROCESSING routine is used to determine the firing angle of the SCR and thus the magnitude of the DC current to be injected into the motor for braking purposes. As discussed in §4.2 above, the actual value of the firing angle is determined by the settings on the magnitude control potentiometers. One acceptable PRE-MAGNITUDE PROCESSING routine may be found at lines 672-694 of the attached appendix.
As discussed above the PRE-MAGNITUDE PROCESSING routine determines the magnitude of the DC current that will be injected into the motor for braking purposes. Because the magnitude of the DC braking current depends on whether the STOP or the E-STOP control switch has been activated, the control logic first determines whether the E-STOP flag is set (i.e., whether the E-STOP control switch has been activated). If the E-STOP detected then the setting of the E-MAGNITUDE potentiometer, signal AN1, (refer to §4.2, above) will control the magnitude of the DC braking current; otherwise the magnitude will be controlled by the setting on the MAGNITUDE potentiometer, signal AN0. After determining the value corresponding to the appropriate braking potentiometer, the control logic then multiples the determined value by a multiplier factor that is based on the previously measured AC line frequency. Appropriate control logic for determining the multiplier factor and multiplying the same may be found in the attached appendix.
In one embodiment of the present invention the predefined value that the match counter must meet before the bits in the Match Register begin to be set is determined by the maximum brake time setting signals provided by the user (e.g., time signals PB7, PC0 and AN2, see §4.2). In this embodiment, the predefined value will be relatively large when a relatively large maximum brake time setting is selected by the used. Similarly, a relatively low predefined value will be selected whenever the maximum braking time is short. The advantage of varying the predefine value according to the maximum braking time is that short braking times generally indicates that the load is small or that the motor must be stopped quickly. For small loads the number of matches required to avoid "dead spots" is generally low and thus a low predefined value can be selected. Accordingly, the predefined value can be reduced without significantly impacting the accuracy of zero speed detection. Likewise, long maximum braking times generally correspond to large loads where a large number of matches may be required to overcome the dead spots associated with large loads and ensure the accuracy of the zero speed detection. Other embodiments are envisioned where the predefined value varies as a function of motor load, motor speed at the time of braking, or other user settings.
Referring back to FIGS. 19A-19B, it may be noted that the ZERO SPEED DETECTION control logic first establishes a sample accumulation register for receiving four samples of the ZERO SPEED SENSE signal AN3 (block 261). The control logic then configures the input port that receives the voltage waveform appearing between the third terminal and the common terminal, see discussion at §4.2.4, to perform an A/D conversion. The control logic then takes four digital samples of the input waveform and sums them together in the sample accumulation register and divides the sum by four to obtain an average sample value (block 262). The average sample value is then compared to the average sample value of the present waveform position from the previous cycle. The average value of the waveform position sample from the previous cycle is referred to herein as the "reference value."
The purpose of the delay routine is to control the firing angle of the SCR and thus to control the magnitude of the DC braking current applied to the motor. As discussed above, the magnitude of the DC braking current directly corresponds to the length of time between the time the input AC waveform crosses zero and the time when a gating pulse is applied to the SCR 67. See §§4.2.3 and 4.2.5, above. In the present invention, the DELAY routine is used to set the time period between the zero cross of the input AC waveform and the firing of the SCR 67.
As illustrated in FIGS. 17A-17B, after generating a firing pulse to the SCR 67 the control logic for the main FIRE routine and determines whether additional firing of the SCR 67 is required. In other words, the control logic determines whether it should continue to provide DC braking current to the motor. There are at least three instances when the control logic should stop providing DC braking current to the motor: (1) when the maximum braking time has expired; (2) when the brake has been manually released; and (3) when zero speed has been detected. To test for these conditions, the FIRE routine first determines whether the maximum braking time has expired (i.e., whether the brake has timed out)(block 294). This is done by comparing the bytes in the timer counter to the maximum timer setting determined by the control signals PB7, PC0 and AN2 discussed in §4.2, above. If the timer counter meets or exceeds the maximum timer setting then the maximum braking time has been met or exceeded. As indicated in blocks 296 and 299 of FIGS. 17A-17B, when the maximum braking time has been met or exceeded, the FIRE routine will (1) clear the timer count; (2) clear the zero cross time register; (3) clear the Match Register used for zero speed detection and (4) return to the execution routine that called the FIRE routine--here, the main SLAVE routine.
If the maximum brake time has not been exceeded, the control logic for the FIRE routine will then determine whether a manual brake release switch has been activated (not illustrated in FIGS. 17A-17B). If the manual brake release switch has been activated, the main routine will clear the counters and registers discussed above and return to the main execution routine. If, however, the manual release was not activated, the control logic will then test to determent if zero speed sensing is enabled (block 297). If zero speed sensing is not enabled, then the control logic will loop back to the start of the FIRE routine and will continue to repeat the FIRE cycle until (1) the maximum brake time expires or is met or (2) the manual brake release switch is activated. If, on the other hand, zero speed sensing is enabled, the control logic will check the Match Register discussed in §4.4.3(b)(4) (block 298), and, if all eight bits in the Match Register are set, will end the FIRE routine by executing the steps at blocks 296 and 299. If the Match Register used by the ZERO SPEED DETECTION routine does not indicate zero speed, then the control logic will loop to the initiation of the FIRE routine and will continue to do so until (1) the maximum brake time is met or exceeded; (2) the manual brake release switch is activated; or (3) the match register for the zero speed detection circuit indicates that zero speed is detected.
One feature of the FIRE routine discussed above is that is flexible both in terms of both the AC input frequency and the firing angle defined by the user settings of the MAGNITUDE control potentiometer. See §4.2. This flexibility is demonstrated by the fact that the FIRE routine will always take eight samples for zero speed detection within the time period beginning after a zero cross is detected and ending when the SCR 67 is fired as illustrated in FIGS. 20A and 20B.
It should also be noted from FIGS. 20A and 20B that in the present invention the samples for the zero speed detection are taken before the trigger pulse for the SCR pulse is generated and during the first 90° of the input AC waveform. This is significant in that it is believed that the optimum waveform positions for sampling to determine zero speed are those positions occurring in the first 90°-180° of the input AC waveform.
As illustrated at block 335 of FIGS. 22A-22B, the control logic for the Holding Brake routine first looks for an assertion of the START signal (PA0). See §4.2.1. When the START signal is detected, the Holding Brake routine ensures that the brake contactor is open and then closes the motor contactor allowing AC power to flow to the motor, thus starting the motor (blocks 336-37). The Holding Brake routine then monitors the looks for an indication that the STOP signal (PA1) has been activated (block 338). Upon detection of the STOP signal, the control logic for the Holding Brake routine (1) opens the motor relay, thus cutting off AC power to the motor (block 339); and (2) closes the brake contactor, thus coupling the brake assembly to the motor (block 340). The Holding Brake routine then executes a fire routine, which in many way is similar to the FIRE routine discussed in §4.3.2(b).
As illustrated in FIGS. 22A-22B, in executing its fire routine, the Holding Brake routine first determines whether the START signal has been asserted, indicating that the braking of the motor should be terminated and the motor started (block 341). If a START signal is detected, the control logic returns to the main Holding Brake routine at block 336, opens the brake contactor and closes the motor contactor to start the motor (block 337). If, however, the control logic does not detect the START signal, it then detects a zero crossing in a manner similar to that discussed above with respect to the slave mode. (block 342). After a zero crossing is detected, the control logic then executes a delay cycle to ensure that the proper firing angle is maintained (block 343). In the holding fire routine, the magnitude of the DC braking current may be determined by a holding magnitude potentiometer, in a manner similar to that discussed in §4.2.3 above. In most instances, the holding magnitude potentiometer will be set such that the magnitude of the DC braking current during a holding brake cycle is less than that for a SLAVE brake cycle. Embodiments are anticipated where a regular DC braking cycle is applied until zero speed is detected and thereafter a reduced holding brake DC current is applied until a START signal is detected.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4093900 *Aug 11, 1976Jun 6, 1978General Electric CompanyDynamic brake blending for an inverter propulsion systemUS4278921 *Aug 31, 1979Jul 14, 1981Consolidated Electronic Industries Proprietary LimitedConstant speed electric motorUS4292577 *Mar 12, 1979Sep 29, 1981Kearney & Trecker CorporationA.C. Motor control circuitUS4568864 *Aug 6, 1984Feb 4, 1986Ex-Cell-O CorporationElectric motor control for a pipe benderUS4749933 *Feb 26, 1986Jun 7, 1988Ben Aaron MaxPolyphase induction motor system and operating methodUS4761600 *Mar 6, 1987Aug 2, 1988General Electric CompanyDynamic brake controlUS4767970 *Dec 22, 1986Aug 30, 1988Ampex CorporationDynamic brake control for a tape drive systemUS4890027 *Nov 21, 1988Dec 26, 1989Hughes Aircraft CompanyDynamic motor controllerUS4904918 *Mar 13, 1989Feb 27, 1990General Electric CompanyPower conversion system including an improved filter for attenuating harmonicsUS4916370 *Apr 26, 1989Apr 10, 1990Allen-Bradley Company, Inc.Motor stoppage apparatus and method using back emf voltageUS5003241 *Feb 15, 1989Mar 26, 1991Allen-Bradley Company, Inc.Motor stoppage detection using back emf voltage* Cited by examinerNon-Patent CitationsReference1 *Ambitech Industries, Inc., Instructions for Short Stop Electronic Motor Brake 1982.2Ambitech Industries, Inc., Instructions for Short-Stop™ Electronic Motor Brake 1982.3 *Ambitech Industries, Inc., Options for Short Stop Electronic Motor Brake (no date).4Ambitech Industries, Inc., Options for Short-Stop™ Electronic Motor Brake (no date).5 *Ambitech Industries, Inc., Short Stop Models Price List, (no date).6Ambitech Industries, Inc., Short-Stop™ Models Price List, (no date).7 *AMC (Auto Motor Controller) Technologies, Inc., brochure, (no date).8Article entitled "Reducing Wind-Down" by Walter Lukitsch, Timber Processing, Sep. 1990.9 *Article entitled Reducing Wind Down by Walter Lukitsch, Timber Processing, Sep. 1990.10 *Braketron Dynamic Electronic Motor Brakes, two page brochure (no date).11Braketron® Dynamic Electronic Motor Brakes, two-page brochure (no date).12 *Digibrake Model B60, MC Technologies, Inc., brochure, (no date).13Digibrake™ Model B60, MC Technologies, Inc., brochure, (no date).14 *Motorola HC05 Technical Data (1990).15 *Motorola Semiconductor Technical Data, Technical Summary 8 bit Microcontroller Unit (1990).16Motorola Semiconductor Technical Data, Technical Summary 8-bit Microcontroller Unit (1990).17 *Motortronics, Inc., Reduced Voltage Motor Starter and Brake LBC3/LBS3 Series 3 to 1000 HP (no date).18 *Nordic Series 98 Solid state Electronic Motor Brake, Instruction Bulletin (Aug. 31, 1988).19 *Nordic Series 98 Solid state Electronic Motor Brake, two page data sheet (no date).20Nordic Series 98 Solid-state Electronic Motor Brake, Instruction Bulletin (Aug. 31, 1988).21Nordic Series 98 Solid-state Electronic Motor Brake, two-page data sheet (no date).22 *Nordic, Solid state Starters, Small Horsepower Starters (6 to 60 amp (no date).23Nordic, Solid-state Starters, Small Horsepower Starters (6 to 60 amp (no date).24 *TASC Drives Inc., Instruction Manual Braketron Dynamic Electronic Motor Brakes (02/90).25TASC Drives Inc., Instruction Manual Braketron® Dynamic Electronic Motor Brakes (02/90).* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS5705863 *May 2, 1995Jan 6, 1998The United States Of America As Represented By The Secretary Of The NavyHigh speed magnetostrictive linear motorUS5838124 *Aug 28, 1997Nov 17, 1998Barber ColmanSystems and methods for braking of actuator and brushless DC motor thereinUS5847530 *Aug 28, 1997Dec 8, 1998Barber ColmanSystems and methods for torque control of actuator and brushless DC motor thereinUS5872434 *Aug 28, 1997Feb 16, 1999Barber Colman CompanySystems and methods for actuator power failure responseUS6037729 *Jan 28, 1998Mar 14, 2000Black & Decker Inc.Apparatus and method for braking electric motorsUS6236177Jun 4, 1999May 22, 2001Milwaukee Electric Tool CorporationBraking and control circuit for electric power toolsUS7100747Apr 18, 2001Sep 5, 2006Reliance Electric Technologies, LlcIntegral motor brake manual release mechanismUS7262571 *Sep 7, 2004Aug 28, 2007Rockwell Automation Technologies, Inc.Resistive braking module with thermal protectionUS7567044 *Mar 21, 2007Jul 28, 2009Japan Servo Co., Ltd.Braking device for an electrically driven rotorUS8133001 *Aug 21, 2007Mar 13, 2012Ares Trading S.A.Device for overturning containersUS8169102 *Jun 4, 2009May 1, 2012Industrial Technology Research InstituteVertical-axis windpower fan unit and module and power generating system thereofUS8878468 *Apr 29, 2011Nov 4, 2014Pratt & Whitney Canada Corp.Electric machine assembly with fail-safe arrangementUS9153996 *Nov 17, 2009Oct 6, 2015Valeo Systemes De Controle MoteurMethod and electric combined device for powering and charging with compensation meansUS9614466May 20, 2015Apr 4, 2017Black & Decker Inc.Electronic braking for a universal motor in a power toolUS20060050462 *Sep 7, 2004Mar 9, 2006Nelson Michael JResistive braking module with thermal protectionUS20070222290 *Mar 21, 2007Sep 27, 2007Shuichi MatsuhashiBraking device for an electrically driven rotorUS20090196726 *Aug 21, 2007Aug 6, 2009Ares Trading S.A.Device for Overturning ContainersUS20100253084 *Jun 4, 2009Oct 7, 2010Industrial Technology Research InstituteVertical-axis windpower fan unit and module and power generating system thereofUS20120019173 *Nov 17, 2009Jan 26, 2012Valeo Systemes De Controle MoteurMethod and electric combined device for powering and charging with compensation meansUS20120275069 *Apr 29, 2011Nov 1, 2012Pratt & Whitney Canada Corp.Electric machine assembly with fail-safe arrangementCN102623966A *Apr 1, 2012Aug 1, 2012许昌许继软件技术有限公司Differential protection method for bus* Cited by examinerClassifications U.S. Classification318/375, 318/759, 318/364, 318/371International ClassificationH02P3/24Cooperative ClassificationH02P3/24European ClassificationH02P3/24Legal EventsDateCodeEventDescriptionNov 29, 1993ASAssignmentOwner name: BALDOR ELECTRIC COMPANY, INC., ARKANSASFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HOPWOOD, KENNETH;REEL/FRAME:006791/0728Effective date: 19931118Dec 7, 1998FPAYFee paymentYear of fee payment: 4Jan 2, 2003REMIMaintenance fee reminder mailedJan 30, 2003SULPSurcharge for late paymentYear of fee payment: 7Jan 30, 2003FPAYFee paymentYear of fee payment: 8Dec 13, 2006FPAYFee paymentYear of fee payment: 12RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services