Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P5/00—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors
  • H02P5/68—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors controlling two or more DC dynamo-electric motors
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
  • H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of DC power input into DC power output
  • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
  • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
  • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
  • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
  • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
  • H02P6/14—Electronic commutators
  • H02P6/16—Circuit arrangements for detecting position
  • H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
  • H02P6/14—Electronic commutators
  • H02P6/16—Circuit arrangements for detecting position
  • H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
  • H02P6/182—Circuit arrangements for detecting position without separate position detecting elements using back-emf in windings
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
  • H02P7/03—Arrangements for regulating or controlling the speed or torque of electric DC motors for controlling the direction of rotation of DC motors
  • H02P7/05—Arrangements for regulating or controlling the speed or torque of electric DC motors for controlling the direction of rotation of DC motors by means of electronic switching
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P8/00—Arrangements for controlling dynamo-electric motors rotating step by step
  • H02P8/42—Arrangements for controlling dynamo-electric motors rotating step by step characterised by non-stepper motors being operated step by step

Definitions

• the invention relates to a DC/DC power supply comprising a transformer, where said transformer has a primary winding with a first end and a second end and two secondary windings, where switching means are arranged in connection with said primary winding, and where a diode is arranged in series with each of said secondary windings.
• a DC/DC power supply in connection with commutated DC motors used in furniture.
• PWM or switch-mode controlled electric motors are well-known in the art and employed in a variety of electric drive applications including one or more electric DC motors.
• Typical applications, to which the present invention pertains include drive arrangements for lifting and lowering of height adjustable furniture components like tabletops, chairs and other resting furniture for domestic, office and medical use, motion control of robot devices etc.
• a DC/DC power supply comprising a transformer, where said transformer has a primary winding with a first end and a second end and two secondary windings, where switching means are arranged in connection with said primary winding, and where a diode is arranged in series with each of said secondary windings, characterized in that the power supply comprises a voltage divider with a centre tab, to which said first end of said primary winding is connected, and in that the second end of said primary winding is connectable to either side of said voltage divider via said switching means.
• said switching means comprises two individually controlled electronic switches for connecting said second end of said primary winding to either side of said voltage divider.
• two individually controlled electronic switches allows the independent supply of each of the two electric motors. This again allows compensation for different loads on each electric motor.
• each of the electronic switches is controlled by means of a microprocessor.
• a microprocessor This allows quick and efficient adaptation of the supply to each of the electric motors according to the momentary load on that motor.
• the use of microprocessors allows several loads to be operated in synchronicity. In that case one microprocessor is assigned to be master and the other slaves.
• the DC/DC power supply further comprises means for detecting the rotation of at least one motor connected to said power supply. Thus, the rotational speed of the motor can be detected and thus the load thereon estimated, so as to adjust the current supply to the motor.
• said means for detecting the rotation of an attached motor comprises means for detecting the back electromotive force from said at least one electric motor. It has been found that in a traditional, mechanically commutated motor, such as a DC motor, a series motor or universal motor, it is possible to detect the back electromotive force in connection with the commutation. Because the number of commutations is strictly linked to the construction of the motor, the number of commutations may directly serve as an indication of the rotation of the motor.
• said means for detecting the back electromotive force comprises an inductor and/or resistor over which a voltage is measured. This turns out to be sufficient to allow the detection of commutation during the pauses in the current supply to the electric motor.
• the microprocessor is adapted to control said at least one motor in dependence of said detection of the rotation of the motor armature.
• the motor to be run in steps corresponding to a number of commutations, thus keep- ing track of the rotational angle, and consequently any directly linked motion, e.g. translatory motion via a gear train.
• the number of steps may be one, the mechanically commutated motor, be it a DC motor, a series motor or universal motor, then effectively functions as a stepper motor.
• the microprocessor is adapted to control a further motor in dependence of said detection of the rotation of the motor armature thereof, and in dependence of the rotation of the motor armature of said at least one motor. This allows two motors to effectively function as stepper motors and consequently to be operated in synchronicity.
• fig. 1 shows a schematic diagram of DC/DC power supply accord- ing to the present invention
• fig. 2 shows a schematic diagram of a DC/DC power supply according the present invention, but especially adapted for the control of DC motors.
• the DC/DC power supply is provided with DC, such as rectified mains, at the positive terminal 1 and the negative terminal 2.
• a voltage divider 3 Between the positive terminal 1 and the negative terminal 2 there is provided a voltage divider 3.
• the voltage divider 3 comprises two capacitors 4, 5 and two resistors 6, 7.
• the two capacitors 4, 5 have the same capacitance and the two resistors 6, 7 the same resistance.
• the intermediate potential is marked 0, but evidently the intermediate poten- tial floats and is subject to variations depending on the current drawn from the voltage divider 3, unless it is stabilized by an external connection to a fixed reference potential.
• the current is intermittently drawn from the voltage divider 3 by a transformer having a primary winding 9 with a first end 10 and a second end 11.
• the transformer has two secondary windings 12, 13 with a common terminal 14, and a first end terminal 15 and a second end terminal 16.
• the two secondary windings 12, 13 are preferably identical in number of turns and direction.
• the primary-to-secondary ratio is preferably 20:4/4 for the applications described, but may evidently differ from that ratio, depending on the actual application.
• reference is made to a transformer it is not operated as a traditional AC transformer, but merely as an inductive energy storage means. This will also become clear for the skilled person, when reading the following part of the description.
• the DC/DC power supply comprises two controlled switches 18, 19.
• the first controlled switch 18 is connected between the first end 10 of the primary winding 9 of the transformer and the positive terminal 1.
• the second controlled switch 19 is connected between the first end 10 of the primary winding 9 of the transformer and the negative terminal 2.
• the controlled switches 18, 19 are semiconductor switches controlled by means of a microprocessor 20. If galvanic separation between the primary winding 9 and secondary winding 12 of the transformer is desired, the control lines to the controlled switches 18, 19 may include optocouplers (not shown).
• Both the controlled switches 18, 19 are operated intermittently by the microprocessor 20, e.g. according to a pulse width modulation scheme.
• the microprocessor 20 ensures that the controlled switches 18, 19 are not active at the same time, but otherwise the microprocessor operates the controlled switches 18, 19 independently of each other.
• the cathodes rather than the anodes of each of the respective diodes could be connected to the respective end terminal 15, 16, thus giving rise to a current in the opposite direction in the unspecified electric loads 22, 24 of fig. 1.
• the direction of the current would be of no significance at all.
• the diodes 21, 23 in either embodiment need not be connected directly to their respective terminal 15, 16 but may be placed anywhere in the circuit between the respective terminal and the node 29. It is however necessary that the diodes 21, 23 are polarized the same way with respect to their respec- tive terminal 15, 16, i.e.
• the controlled switches 18, 19 may be controlled independently of each other, it is possible to control the supply to two loads 22, 24 independently of each other using only one single transformer.
• the two controlled switches 18, 19 may be controlled in an alternating manner, the first controlled switch 18 being in the active part of its duty cycle, while the second controlled switch 19 is in its inactive part of the duty cycle, and vice versa.
• the first controlled switch 18 performing a number of duty cycles without the second controlled switch 19 being active at all, and vice versa.
• Fig. 2 shows an embodiment of the invention especially adapted for the control of mechanically commutated electric DC motors.
• the DC motors could be a permanent magnet motors, but also series motors or universal motors may be operated using the power supply according to the invention.
• the general construction of the DC/DC power supply ac- cording to this embodiment is largely the same as for the embodiment first described. For the sake of clarity, the same reference numerals will be maintained for the same parts, and the description thereof will only be repeated to the extent necessary for the understanding of the differences.
• change-over switches 25, 26 for reversing the polarity in the supply lines to the motors 221, 241 have been introduced.
• the change-over switches are preferably solid state switches controlled by the microprocessor 20.
• the microprocessor 20 is preferably adapted to operate the change-over switches 25, 26 in no-current conditions only in order to avoid unnecessary stress.
• the change-over switches 25, 26 do thus not have to have any load-breaking capacity.
• the microprocessor prevents the two change-over switches 25, 26 from assuming conditions where the secondary windings 12, 13 are short circuited.
• each of the diodes 21, 23 is connected to a re- spective end terminal 15, 16 of the secondary winding.
• the cathodes, rather than the anodes, of each of the respective diodes 21, 23 could be connected to the respective end terminal 15, 16, thus giving rise to a current in the opposite direction in the respective electric motor 221, 241 of fig. 1. This would of course lead to the motors rotating in the opposite directions, but since this is easily changed by means of the change-over switches 25, 26, this would not constitute any problem.
• the embodiment of fig. 2 further comprises two inductors and/or resistors 27, 28 placed in series with a respective one of said first motor 221 and second motor 241. These inductors and/or re- sistors 27, 28 serve as means for measuring the back electromotive force from the respective commutated electric DC motors 221, 241.
• the inventors of the present invention have realized that the back electromotive force from the motors is readily detectable and may thus be used as a means for determining the angular position of the armature of the DC motor, provided of course that the number of commutations per revolution of the motor 221, 241 is known.
• the commutations are detected by the microprocessor 20 by means of a voltage measured over the inductors 27, 28, possibly using appropriate additional circuitry, not shown.
• the microprocessor 20 may increase the duty cycle ratio for that motor, or decrease the duty cycle ratio for the other motor according to a predetermined scheme, which depends on the ap- plication, and does thus not form part of this invention.
• the duty cycle ratio being understood as the ratio between the time the switching means is active to the sum of an active-inactive cycle.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)
• Control Of Multiple Motors (AREA)
• Control Of Direct Current Motors (AREA)
• Control Of Stepping Motors (AREA)

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Publications (1)

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• 2006
  • 2006-09-01 KR KR1020087008116A patent/KR20080056188A/ko not_active Ceased
  • 2006-09-01 RU RU2008113216/09A patent/RU2387073C2/ru not_active IP Right Cessation
  • 2006-09-01 US US12/065,570 patent/US8022652B2/en not_active Expired - Fee Related
  • 2006-09-01 DE DE602006019748T patent/DE602006019748D1/de active Active
  • 2006-09-01 CN CN2006800323393A patent/CN101258673B/zh not_active Expired - Fee Related
  • 2006-09-01 BR BRPI0615741-6A patent/BRPI0615741A2/pt not_active IP Right Cessation
  • 2006-09-01 WO PCT/DK2006/000476 patent/WO2007028385A1/en not_active Ceased
  • 2006-09-01 JP JP2008528345A patent/JP2009507455A/ja active Pending
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  • 2006-09-01 CN CN201210289432XA patent/CN102801372A/zh active Pending
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