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WO2008000264A1 - Procédé d'attaque d'une charge inductive - Google Patents

Procédé d'attaque d'une charge inductive Download PDF

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Publication number
WO2008000264A1
WO2008000264A1 PCT/DK2007/000315 DK2007000315W WO2008000264A1 WO 2008000264 A1 WO2008000264 A1 WO 2008000264A1 DK 2007000315 W DK2007000315 W DK 2007000315W WO 2008000264 A1 WO2008000264 A1 WO 2008000264A1
Authority
WO
WIPO (PCT)
Prior art keywords
inductive load
switching element
current
power source
terminals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/DK2007/000315
Other languages
English (en)
Inventor
Nils Christensen
Rune Thomsen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Danfoss Deutschland GmbH
Original Assignee
Danfoss Compressors GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Danfoss Compressors GmbH filed Critical Danfoss Compressors GmbH
Publication of WO2008000264A1 publication Critical patent/WO2008000264A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
    • H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
    • H02M7/48—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current

Definitions

  • the present invention relates to a method of driving an inductive load in such a manner that demagnetisation currents which are introduced in the inductive load are allowed to decay. More particularly, the present invention relates to a method as defined above in which the energy losses in an electrical circuit having the inductive load inserted therein are reduced as compared to prior art methods.
  • the method of the present invention is very suitable for driving the coils of a multiphase direct current (DC) motor.
  • FIG. 1 illustrates an electrical circuit 1 with an inverter 2 comprising six switching elements Tr T 6 .
  • the inverter 2 is coupled to terminals of a DC power source 3 and to a motor 4.
  • the motor 4 is a three phase motor, i.e. it comprises three motor coils A, B and C.
  • a controller (not shown) controls switching of the switching elements TrT 6 between their open and closed states in order to obtain appropriate commutation of the motor coils A, B, C.
  • Each of the switches TrTe has a diode DrD 6 associated with it.
  • FIG. 2 A typical switching sequence is illustrated in Fig. 2.
  • the ON and OFF states are shown as a function of time with time divided into sequence steps of an appropriate duration. It is clear from Fig. 2 that the switching elements T 1 -T 6 are sequentially opened and closed. Accordingly, the motor coils A, B, C are sequentially connected to and disconnected from the terminals of the DC power source 3. The resulting switching pattern for the motor coils A, B, C as a function of time is illustrated in Fig. 3. In Fig.
  • the controller When the controller switches from one step to the next, the motor coil which was previously excited, but is now disconnected from the DC power source 3, will experience a current which continues to flow in the same direction as before. This is due to the inductive nature of the coil. This current is known as the demagnetisation current, and it will decrease to zero.
  • the demagnetisation current In the electrical circuit 1 shown in Fig. 1 and using the switching sequence illustrated in Fig. 2 the demagnetisation current will run through one of the diodes D 1 -De- Thereby energy is dissipated in the relevant diode, and this leads to an energy loss in the circuit.
  • the components used for the electrical circuit 1 in particular the diodes Di-D 6 , must be able to withstand the relatively large demagnetisation currents which will run through the circuit 1. Thereby it may be necessary to chose relatively expensive components in order to ensure reliable operation of the circuit 1.
  • Fig. 4 shows the current flow during step 1 as defined by the switching sequence of Fig. 2.
  • switching elements Ti and T 5 are closed while the remaining switching elements are open.
  • motor coil A is connected to the positive terminal of the DC power source 3
  • motor coil B is connected to the negative terminal of the DC power source 3
  • motor coil C is disconnected from the DC power source 3.
  • the current will run through motor coils A and B as indicated by the arrows.
  • switching element T 5 is opened and switching element Te is closed.
  • motor coil B is disconnected from the DC power source 3
  • motor coil C is connected to the negative terminal of DC power source 3.
  • an object of the invention to provide a method for driving an inductive load arranged in an electrical circuit, in such a manner that the total efficiency of the circuit is improved.
  • a method for driving an inductive load arranged in an electrical circuit further comprising at least two switching elements and a direct current (DC) power source having a set of terminals comprising the steps of:
  • the term 'inductive load' should be interpreted to mean a component or a number of interconnected components, having an inductive nature, and being capable of being connected across the terminals of the DC power source.
  • the inductive load may advantageously be or comprise one or more coils or windings.
  • the inductive load comprises two or more inductive components, such as two or more coils or windings, these may be connected in series and/or in parallel.
  • the inductive load may further comprise one or more components which do not have an inductive nature, such as one or more capacitors and/or one or more resistors.
  • the electrical circuit comprises at least two switching elements.
  • the term 'switching element' should be interpreted to mean an element which is adapted to switch between a closed state and an open state. In the closed state the switching element establishes an electrical connection between components arranged on opposite sides of the switching element, and in the open state such a connection is interrupted.
  • the switching elements are preferably ordinary switches, such as Mosfets or IGBTs.
  • the electrical circuit also comprises a DC power source, i.e. a power source which delivers DC power.
  • the DC power source may advantageously be a battery.
  • the inductive load is connected to the terminals of the DC power source. This is done by closing at least a first switching element, and it may optionally involve closing at least one additional switching element. While the inductive load is connected to the terminals of the DC power source a current runs through the inductive load. Due to the inductive nature of the inductive load, a magnetic field is thereby induced in the inductive load.
  • the first switching element is opened, and thereby the connection between the inductive load and the terminals of the DC power source is interrupted. Accordingly, the DC power source no longer supplies a current to the inductive load.
  • a demagnetisation current will continue to flow from the inductive load, or from an inductive component of the inductive load.
  • at least a second switching element is closed, thereby connecting the inductive load to a current sink.
  • the term 'current sink' should be interpreted to mean a point in the electrical circuit to which the demagnetisation current can run with no or only very little energy dissipation in the components of the electrical circuit.
  • the current sink may, e.g., be a terminal of the DC power source.
  • the demagnetisation current may be allowed to circulate in the electrical circuit, or in part of the electrical circuit, until it has decayed to an acceptable level.
  • a minimum level may, e.g., be zero, or it may be a threshold value defining an acceptable level for the demagnetisation current. This will be described in further detail below.
  • the demagnetisation current is allowed to decay in the manner described above because it is thereby avoided that energy is dissipated in the components of the electrical circuit, and thereby the total efficiency of the electrical circuit can be improved.
  • the total efficiency is approximately 94%.
  • the total efficiency can be increased to approximately 98%.
  • the requirements to the components of the electrical circuit are reduced, and it is thereby possible to use less expensive components. Thereby the manufacturing costs can be reduced without compromising the performance of the electrical circuit.
  • the method may be introduced on existing electrical circuits without increasing the component count.
  • the time interval elapsing from closing the first switching element until opening the first switching element may be substantially longer than the time interval elapsing from closing the second switching element until opening the second switching element.
  • the time interval during which the second switching element is closed in order to allow the demagnetisation current to decay is very brief as compared to the time interval during which the inductive load is connected to the terminals of the DC power source. It should be noted that during the time interval in which the inductive load is connected to the terminals of the DC power source, the connection may actually be connected and disconnected rapidly. This is, e.g., the case when a pulse width modulation (PWM) control strategy is used. This will be further described below.
  • PWM pulse width modulation
  • the length of the time interval during which the demagnetisation current is allowed to decay will depend upon the load, the specific application and the ambient temperature. In a preferred embodiment in which the method is used for driving a DC motor the time interval will depend on the speed of the motor. This is because at maximum speed the motor is capable of delivering maximum torque. This has the consequence that the magnetisation current in the motor is maximised, and thereby it will take longer for the demagnetisation current to decay.
  • the method may further comprise the step of monitoring the demagnetisation current, and the second switching element may be opened when it is determined that the demagnetisation current has decayed to a predefined threshold level.
  • the time interval during which the demagnetisation current is allowed to decay does not have a fixed length. Instead the length of the time is determined by the time it takes for the demagnetisation current to decay to the predefined threshold value.
  • the second switch is opened when the demagnetisation current has reached an 'acceptable' level.
  • the predefined threshold value may be zero, i.e. the second switch is opened when it has been found that the demagnetisation current has decayed completely.
  • the predefined threshold value may be a level which is larger than zero, but sufficiently small to ensure that no, or only an insignificant amount of, energy is dissipated in the components of the electrical circuit as a result of the decay of the demagnetisation current.
  • the demagnetisation current may, e.g., be monitored by means of a microcontroller.
  • the time interval during which the demagnetisation current is allowed to decay may have a fixed length, e.g. chosen as a representative duration during which the demagnetisation current will, in the application in question, almost certainly have decayed to zero.
  • the electric circuit may comprise at least two inductive loads and at least four switching elements, and the method may further comprise the steps of:
  • the electrical circuit comprises at least two inductive loads which may be connected to and disconnected from the terminals of the DC power source as described above.
  • Each of the inductive loads may further be connected to the current sink in order to allow the induced demagnetisation current to decay.
  • the first switching element and the third switching element may be operated sequentially, thereby providing a switching pattern.
  • the two or more inductive loads may be connected to/disconnected from the terminals of the DC power source in a sequential manner. This is, e.g., relevant when the method is used for driving a multiphase DC motor, such as a three-phase DC motor. It should be noted that the method of the present invention may be extended to driving three, four, five, etc. inductive loads in the electrical circuit in the manner described above.
  • the switching pattern may be provided by a pulse amplitude modulation (PAM) control strategy.
  • the switching pattern may be provided by a pulse width modulation (PWM) control strategy.
  • PAM pulse amplitude modulation
  • PWM pulse width modulation
  • each of the switching elements may be used for connecting an inductive load to the terminals of the DC power source as well as for connecting an inductive load to the current sink.
  • the switching elements have multiple functions, and the method may thereby be realised without increasing the component count of the electrical circuit, and thereby without increasing the manufacturing costs.
  • the method may be used for driving a DC motor, e.g. a brushless DC motor.
  • the motor may preferably be a multiphase motor, such as a three phase motor.
  • the motor may suitably be used for driving a compressor, e.g. a compressor for use in a refrigeration system.
  • the step of closing the second switching element may be performed immediately after the step of opening the first switching element.
  • the inductive load is connected to the current sink immediately after it has been disconnected from the terminals of the DC power source. Thereby the demagnetisation current is immediately allowed to decay via this path, and dissipation of energy in the components of the electrical circuit due to the decay of the demagnetisation current is thereby avoided to the greatest extent possible.
  • an electrical circuit comprising:
  • DC direct current
  • control unit adapted to operating the switching elements in order to switch them between an open state and a closed state
  • inductive load and the switching elements are arranged relatively to each other in such a manner that closing a first switching element causes the inductive load to be connected to the terminals of the DC power source, and in such a manner that closing a second switching element causes the inductive load to be connected to a current sink, thereby allowing a demagnetisation current induced in an inductive component of the inductive load to decay.
  • the electrical circuit is very suitable for performing the method according to the first aspect of the invention.
  • the control unit may be adapted to perform the method according to the first aspect of the invention, Accordingly, the remarks set forth above are equally applicable here.
  • Fig. 6 shows an electrical circuit during decay of a demagnetisation current in accordance with the method of the invention
  • Fig. 7 shows a switching sequence for the electrical circuit illustrated in Figs. 1 and 4-6, and in accordance with the method of the invention.
  • Fig. 6 illustrates the step of the method of the invention, in which a demagnetisation current induced in motor coil B is allowed to decay via a current sink. Comparing Fig. 6 to Fig. 5 it is clear that switching element J 2 has been closed. Thereby the demagnetisation current which was induced in motor coil B while it was connected to the terminals of the DC power source 3, as illustrated in Fig. 4 and described above, is allowed to decay via the connection established by switching element T 2 as illustrated by the arrows. Since this path represents a much smaller resistance than the alternative path via diode D 2 , the current will run this way rather than via diode D 2 . Thereby no energy is dissipated in diode D 2 during the decay of the demagnetisation current.
  • Fig. 7 shows a switching sequence for the electrical circuit illustrated in Figs. 1 and 4-6, and in accordance with the method of the present invention.
  • Fig. 7 shows the switching sequence as a function of time, the numbers at the bottom indicating step number. Comparing the switching sequence illustrated in Fig. 2 with the switching sequence illustrated in Fig. 7 it is clear that the original switching sequence is maintained, i.e. the motor coils A, B and C are sequentially connected to the terminals of the DC power source 3 as described above with reference to Fig. 2.
  • the switching elements are briefly switched to their ON states, i.e. they are briefly closed. For instance, when moving from step 1 to step 2, switching element T 5 is opened and switching element T 6 is closed.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

L'invention concerne un procédé d'attaque d'une charge inductive (A, B, C) montée dans un circuit électrique (1) comprenant en outre au moins deux éléments de commutation (T1T6) et une source de courant continu (3) présentant un groupe de bornes. Le procédé comprend les étapes consistant à fermer un élément de commutation de manière à connecter la charge inductive aux bornes ; à ouvrir l'élément de commutation de manière à déconnecter la charge inductive ; à fermer un deuxième élément de commutation de manière à connecter la charge inductive à un récepteur de courant pour assurer la décroissance lente d'un courant de démagnétisation dans la charge inductive ; et à ouvrir le deuxième élément de commutation lorsque le courant de démagnétisation atteint un niveau minimal. Le procédé de l'invention permet d'assurer la décroissance lente du courant de démagnétisation sans utiliser de diode, et donc sans dissipation d'énergie dans la diode, ce qui permet d'améliorer l'efficacité du circuit. Le procédé permet en outre de réduire les caractéristiques nominales des composants du circuit électrique et donc d'utiliser des composants meilleur marché.
PCT/DK2007/000315 2006-06-29 2007-06-28 Procédé d'attaque d'une charge inductive Ceased WO2008000264A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA200600872 2006-06-29
DKPA200600872 2006-06-29

Publications (1)

Publication Number Publication Date
WO2008000264A1 true WO2008000264A1 (fr) 2008-01-03

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK2007/000315 Ceased WO2008000264A1 (fr) 2006-06-29 2007-06-28 Procédé d'attaque d'une charge inductive

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WO (1) WO2008000264A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10017186A1 (de) * 2000-04-07 2001-10-18 Msb Elektronik Und Geraetebau Vorrichtung und Verfahren zur Spannungsstellung eines elektrischen Verbrauchers
WO2003094331A1 (fr) * 2002-05-03 2003-11-13 Minebea Co. Ltd. Convertisseur de puissance
US20040062066A1 (en) * 2000-12-22 2004-04-01 Crocker Timothy Richard Switched mode circuit topologies
EP1508957A1 (fr) * 2003-08-22 2005-02-23 Alcatel Dispositif de contrôle du flux d'énergie dans un système de conversion d'énergie
EP1615325A2 (fr) * 2004-07-07 2006-01-11 Nissan Motor Co., Ltd. Conversion de puissance et véhicule

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10017186A1 (de) * 2000-04-07 2001-10-18 Msb Elektronik Und Geraetebau Vorrichtung und Verfahren zur Spannungsstellung eines elektrischen Verbrauchers
US20040062066A1 (en) * 2000-12-22 2004-04-01 Crocker Timothy Richard Switched mode circuit topologies
WO2003094331A1 (fr) * 2002-05-03 2003-11-13 Minebea Co. Ltd. Convertisseur de puissance
EP1508957A1 (fr) * 2003-08-22 2005-02-23 Alcatel Dispositif de contrôle du flux d'énergie dans un système de conversion d'énergie
EP1615325A2 (fr) * 2004-07-07 2006-01-11 Nissan Motor Co., Ltd. Conversion de puissance et véhicule

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