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(12) United States Patent (10) Patent No.: US 7,359,166 B2 Skauen (45) Date of Patent: Apr

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(12) United States Patent (10) Patent No.: US 7,359,166 B2 Skauen (45) Date of Patent: Apr USOO7359166B2 (12) United States Patent (10) Patent No.: US 7,359,166 B2 Skauen (45) Date of Patent: Apr. 15, 2008 (54) METHOD AND CONTROL SYSTEM FOR 5,128,500 A * 7/1992 Hirschfeld .................. 2OOfS R CONTROLLING ELECTRIC MOTORS 5,189,412 A * 2/1993 Mehta et al. .......... 340/825.22 5,661,625 A * 8/1997 Yang ........................... 361.92 (75) Inventor: Ronny Skauen, Gressvik (NO) 6,169,648 B1* 1/2001 Denvir et al. ................. 361.25 6,234,100 B1* 5/2001 Fadeley et al. ......... 114/144 R (73) Assignee: Sleipner Motor AS, Fredrikstad (NO) 6,570,272 B2 * 5/2003 Dickhoff..................... 307 113 (*) Notice: Subject to any disclaimer,- 0 the term of this (Continued) patent is extended or adjusted under 35 FOREIGN PATENT DOCUMENTS U.S.C. 154(b) by 493 days. EP O 651 489 5, 1995 (21) Appl. No.: 10/618,265 (Continued) (22) Filed: Jul. 11, 2003 Primary Examiner Michael Sherry Assistant Examiner—Ann T. Hoang (65) Prior Publication Data (74) Attorney, Agent, or Firm—Lipsitz & McAllister LLC US 2004/OO85695A1 May 6, 2004 (57) ABSTRACT (30) Foreign Application Priority Data There is described a method for controlling an electric motor comprising an operating relay having relay windings with Oct. 30, 2002 (NO) ................................. 2002 52O7 respective first and second relay contacts and a control (51) Int. Cl. means, which motor via current conductors is connected to HO2H 7/08 (2006.01) said relay and a power source wherein an operator by using (52) U.S. Cl. ........................................................ 361A23 said control means controls the application of current to the (58) Field of Classification Search .................. 361/33, motor armature or rotor and field coil(s) or field magnet(s), 361/23 monitoring devices are provided which sense indicating See application file for complete search history. parameters that are compared with respective corresponding reference values in a safety function unit in order to deter (56) References Cited mine whether the contacts of the operating relay are mis takenly in the on position, and if one of the contacts is the U.S. PATENT DOCUMENTS on position, ensures the Switching on of at least the other one 3,656,023 A * 4, 1972 Hadfield ...................... 361.26 of the relay contacts so that the current application to the 3,671,834. A * 6/1972 Buckeridge .. ... 318,293 motor is interrupted and the motor stops. There is also 3,898,527 A * 8/1975 Cawley ....................... 361.23 described a control system for an electric motor, wherein 3,911,341 A * 10/1975 Carlson et al. ............. 388,829 sensors/sensing means are provided arranged at Suitable 4,027.202 A * 5/1977 Tyler et al. ................... 361/33 measuring points in the system or motor circuit connected to 4,151,575 A * 4/1979 Hogue ............ ... 361/33 the safety function unit and arranged so that when there is no 4.389,692 A * 6/1983 Sander et al. ... ... 361 29 4,477,753 A * 10/1984 Ratzel et al. ............... 318/.563 control signal to the relays, the contacts of both relays are 4,638,850 A * 1/1987 Newell et al. .............. 165,255 energized and the motor stops. 4.942,346 A 7, 1990 Ardit et al. 4,972,133. A * 11/1990 Hirota et al. ............... 318,646 4 Claims, 3 Drawing Sheets 13 US 7,359,166 B2 Page 2 U.S. PATENT DOCUMENTS JP 2216726 8, 1990 JP 5049314 3, 1993 6,657,833 B2 * 12/2003 Matsuki et al. ............... 361.23 JP 101.45909 5, 1998 FOREIGN PATENT DOCUMENTS GB 1523 599 9, 1978 * cited by examiner U.S. Patent Apr. 15, 2008 Sheet 1 of 3 US 7,359,166 B2 Fig. 1 (PRIOR ART) U.S. Patent Apr. 15, 2008 Sheet 2 of 3 US 7,359,166 B2 U.S. Patent Apr. 15, 2008 Sheet 3 of 3 US 7,359,166 B2 US 7,359,166 B2 1. 2 METHOD AND CONTROL SYSTEM FOR controls the application of current to the motor armature or CONTROLLING ELECTRIC MOTORS rotor and field coil(s) or field magnet(s), which method is characterised in that a Voltage is sensed which is indicative BACKGROUND OF THE INVENTION of the Voltage at the relay winding, which Voltage is com pared with a reference voltage and if the voltage is found to The invention relates to a method and control system for be too low in relation to a threshold value at which the relay controlling electric motors, especially motors carrying rela does not fail, but is close to doing so, the power Supply to tively strong current. Such motors are widely used for the the relevant relay winding is cut off, and a delay device is operation of ship thrusters where it is also particularly activated which, prior to reapplication of approved Voltage important to assure reliable operation. 10 to the relevant relay winding after an interruption because of Normally, direct-current motors are used, and the current excessively low voltage, will be effected at a lower fre to both the motor rotor or armature and the field coils or field quency than without the delay device. magnets is connected via an operating relay. The operation According to the invention there is also provided a control and the direction of rotation of the motor is controlled by system for an electric motor, comprising an operating relay means of a joystick or the like that is connected to a power 15 having relay windings with respective relay contacts, a Source Such as a battery and via the operating relay provides control means, which motor via current conductors is con the desired power supply to the motor. nected to the relay and a power Source, wherein an operator One problem that may arise is that the operating relay or by using the control unit controls the application of current the main relay of the motor becomes locked in the on to the motor armature or rotor and field coil(s) or field position, usually as a consequence of low Voltage and magnet(s) in Such manner that the operation of the motor is Subsequent relay failure and/or strong current, but also for controlled, characterised in that the system further com other reasons. The motor will then rotate uncontrollably prises a safety function unit and there are provided sensors/ until the main power Switch of the operating system is sensing means arranged at Suitable measuring points in the switched off. This will easily take some second or minutes system or motor circuit connected to the unit and arranged for an unskilled or inexperienced user or skipper. If the 25 so that when there is no control signal to the relays, the motor operates a thruster which pushes the boat to port or to contacts of both relays are energised and the motor stops. starboard in narrow stretches or water, the consequence may In one aspect of the invention, the control system is be personal injury and material damage. characterised in that the safety function unit is provided with The object of the invention is to provide a method for terminals which via wires are connected to the control unit, controlling electric motors and a control system for electric 30 wires are connected to one side of the respective relay motors which intend to eliminate the problems of the windings, so that the Voltage at the windings can be sensed aforementioned type. and given as a signal to the connected terminals on the unit, whose opposite sides are connected via wire to the power BRIEF SUMMARY OF THE INVENTION Source, and terminals are connected to, in the open position 35 of the relay, non-energised relay contacts, or other Suitable According to the invention there is provided a method for measuring points in the system or motor circuit, for controlling an electric motor comprising an operating relay example, at the transition between the armature and the field having relay windings with respective first and second relay coil(s) so that it can be sensed whether the relay contacts are contacts and a control means, which motor via current in an on position (energised), wherein the sensed value can conductors is connected to the relay and a power Source 40 be compared with a reference value, and the sensed position wherein an operator by using the control means controls the is given as a signal to the terminals, and the signals from the application of current to the motor armature or rotor and respective relay contacts and the relay windings are com field coil(s) or field magnet(s), and the invention is charac pared in the unit, and a device is provided in the unit which terised in that monitoring devices are provided which sense in the event of a discrepancy between the respective com indicating parameters that are compared with respective 45 pared signals immediately applies an operating signal to the corresponding reference values in a safety function unit in opposite side of the relevant relay winding, so that the order to determine whether the contacts of the operating electric circuit is broken and the motor stops. relay are mistakenly in the on position, and if one of the In another aspect of the invention, the control system is contacts is the on position, ensures the Switching on of at characterised in that the unit further comprises a terminal least the other one of the relay contacts so that the current 50 which via a wire is connected to a wire connected to a application to the motor is interrupted and the motor stops.
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