EP2572444A2 - Driver circuit and method for controlling a capacitive element - Google Patents

Driver circuit and method for controlling a capacitive element

Info

Publication number
EP2572444A2
EP2572444A2 EP11721479A EP11721479A EP2572444A2 EP 2572444 A2 EP2572444 A2 EP 2572444A2 EP 11721479 A EP11721479 A EP 11721479A EP 11721479 A EP11721479 A EP 11721479A EP 2572444 A2 EP2572444 A2 EP 2572444A2
Authority
EP
European Patent Office
Prior art keywords
switch
drive circuit
capacitive element
primary switch
primary
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.)
Withdrawn
Application number
EP11721479A
Other languages
German (de)
French (fr)
Inventor
Göran Cewers
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.)
Shenzhen Mindray Bio Medical Electronics Co Ltd
Original Assignee
Mindray Medical Sweden AB
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 Mindray Medical Sweden AB filed Critical Mindray Medical Sweden AB
Publication of EP2572444A2 publication Critical patent/EP2572444A2/en
Withdrawn legal-status Critical Current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
    • 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
    • H02M3/33569—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 having several active switching elements
    • H02M3/33576—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 having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33584—Bidirectional converters
    • 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
    • H02M3/33569—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 having several active switching elements
    • H02M3/33576—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 having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33592—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 having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/802—Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits

Definitions

  • the invention pertains to a drive circuit and a
  • the invention pertains to a Bipolar Buck-Boost Regulator for driving at least one piezoactuator.
  • piezoactuators are increasingly replacing electromagnetic actuators.
  • Piezo ceramic technology enables the manufacture of actuators with considerably faster response times and considerably lower energy consumption.
  • the use of this technology brings with it other technological challenges.
  • One of these is the electrical control of piezoactuators.
  • Piezoactuators require voltages of up to 1000V so that they can be actuated to their entire range. However, with modern ceramic multi-layer technology these voltages have been successfully brought down to the 100V range, a
  • a piezoelectric actuator In its construction, a piezoelectric actuator is very similar to a ceramic multilayer capacitor, and the combination of relatively large capacitance and high voltages provides for considerable amounts of energy being storable in these actuators.
  • the advantage of this stored energy is that the actuator state is retained if the electrical connection is cut, and thus no energy is needed to maintain the state.
  • the drawback is that stored energy must be dealt with if the actuator is to be controlled back to a lower movement amplitude. In linear control applications, this involves a great deal of this energy being lost for
  • piezo ceramic structure is subject to inherent friction, which means that piezoactuators are subject to mechanical hysteresis of approximately 20% magnitude. Therefore, in order not to lose motion, one can supply the actuator with a negative voltage of approximately 20% of the normal positive control voltage. The actuator should not be supplied with more negative voltages exceeding 20% of the maximum positive voltage, since this can destroy it.
  • One way of getting rid of many of the mentioned issues is by means of using a switching technique in combination with an inductor.
  • the stored energy in the power supply unit can then be switched back to the actuator.
  • the object of the invention is to provide a switched, energy recovery control of a capacitive element without using a high voltage source.
  • embodiments of the present invention seek primarily to mitigate, alleviate or eliminate one or more of the above-identified deficiencies or disadvantages in the art, singly or in any combination, and solves at least partly the abovementioned issues by providing a device and method according to the appended patent claims.
  • a device and a method are disclosed. This is achieved by means of a
  • Embodiments comprise a method of charging or discharging a capacitive element, preferably a piezoelectric crystal. A device charges a capacitive element according to this method.
  • the device comprises a bipolar buck-boost converter, whereby a
  • a drive circuit which is configured to control a capacitive element.
  • the drive circuit comprises a combined switched boost regulator circuit and a switched buck regulator circuit, as well as a plurality of change-over switches.
  • the drive circuit has two operative states which are selectable using the abovementioned change-over switches, wherein one operative state is a boost regulator and the other operative state is a buck regulator.
  • the abovementioned change-over switches comprises at least four switches, of which a first primary switch SI and a second primary switch S2 are arranged on a primary side and a first secondary switch S3 and a second secondary switch S4 are arranged on a secondary side.
  • the drive circuit comprises at least one inductor which on the primary side preferably has at least two windings LI and L2.
  • the operative states may be obtained as follows:
  • the capacitive element X is earthed on one side, both the secondary switches S3 and S4 are placed on one side of the inductor's secondary winding L3, and a diode D2 is arranged between the second primary switch S2 and the primary inductor winding L2.
  • the circuit is built to drive capacitive elements, such as an actuator element, preferably a piezoactuator .
  • the circuit is built with a boost regulator combined with a buck regulator by using an inductance/coil with more windings on the primary side and extra switches. Thanks to this
  • the drive circuit can control the capacitive element by charging with either positive or negative voltages by switching the circuit to either a positive boost converter or a negative boost converter.
  • the capacitive element can also be discharged by switching the circuit to a positive buck converter, which discharges with energy recovery and feedback to the device power supply. This means that the energy accumulated in the actuator that would otherwise be lost as heat when an
  • the negative control range to the actuator is also restricted. This means that when the drive circuit is used to control the actuator with a negative voltage, so as not to lose movement due to mechanical hysteresis, it is not possible to control the circuit at such high negative voltages that the actuator is destroyed.
  • This limit on actuator capacity is in the range of 20% of the maximum permitted positive voltage.
  • the switches should preferably be MOS transistors, but are not limited to this.
  • the invention comprises a method for driving and controlling capacitive elements.
  • the method comprises providing a combined switched boost regulator circuit and a switched buck regulator circuit as well as a number of change-over switches, and providing two optional operative states by controlling these change-over switches, wherein one operative state is a boost regulator and the other a buck regulator.
  • the boost regulator is used at negative and positive voltages to charge the capacitive element, such as an actuator element, preferably a piezoactuator, and the buck regulator is used to discharge the capacitive element by energy recovery and feedback to the drive circuit power supply .
  • a negative control range for the actuator is limited, such as limited to a range of 20% of the maximum permitted positive voltage.
  • an actuator element such as an actuator element, preferably a
  • piezoactuator can be driven both with positive and negative voltages and be discharged without the energy accumulated in the actuator being lost, e.g. as heat, but can be recovered by feedback to the device power supply.
  • Figure 1 shows a schematic view of an exemplary
  • Figure 2 shows a schematic view of an equivalent to the electrical circuit shown in Figure 1, connected as a positive boost converter;
  • Figure 3 shows a schematic view of an equivalent to the electrical circuit shown in Figure 1, connected as a negative boost converter;
  • Figure 4 shows a schematic view of an equivalent to the electrical circuit shown in Figure 1, connected as a positive buck converter;
  • Figure 5 shows a schematic view of yet another
  • Fig. 6 is a flowchart of a method 10. Description of Embodiments
  • Figure 1 shows a schematic view of an exemplary
  • the inductor has a winding ratio Nl and N2 on the primary side, and N3 on the secondary side.
  • Figure 2 shows a schematic view of an equivalent to the electrical circuit as shown in Figure 1, where S2 and S3 are open and S4 is closed. In this configuration the circuit is operative as a positive boost converter. Energy is switched by means of SI from Vcc and the tank capacitor C.
  • Figure 3 shows a schematic view of an equivalent to the electrical connection as shown in Figure 1, where SI and S4 are open and S3 is closed. In this configuration the
  • connection acts as a negative boost converter. Energy is switched with the help of S2 from Vcc and tank capacitor C. Diode Dl together with the inductor's winding ratio limits the controllable negative voltage to the capacitive element to the required fraction of Vcc.
  • Figure 4 shows a schematic view of an equivalent to the electrical circuit as shown in Figure 1, when SI and S2 are open and S4 is closed. In this configuration the circuit is operative as a positive buck converter. Energy is switched by means of S3 from the capacitive element X to the tank capacitor C.
  • Figure 5 shows a schematic view of yet another
  • the capacitive element X is earthed on one side, and the switches S3 and S4 are arranged on one side of the inductor's
  • D2 prevents the abovementioned clamping effect upon negative boost, which means that high negative voltages can be
  • FIG. 1 shows a schematic view of this equivalent to the electrical circuit as shown in Figure 1, wherein S2 and S3 are open and S4 is closed.
  • a boost via L3 generates a negative voltage across X, or a boost across LI which ramps energy stored in the transformer back to C and supply voltage Vcc.
  • the active boost process is determined by the voltage across the capacitive element (the piezo crystal) X, Vcc and the transformer ratio N3:N1. In practice this means that the negative boost is limited to
  • This process is active when crystal X is to be
  • Figure 4 shows a schematic view of this equivalent to the electrical circuit as shown in Figure 1, where SI and S2 are open and S4 is closed.
  • the capacitive element is a piezoactuator, it may very advantageously be controlled by the circuit of embodiments.
  • the Bipolar Buck-Boost Regulator may be used for driving at least one piezoactuator.
  • the piezoactuator may be an actuator in a valve.
  • the valve may be a respiratory valve in a medical ventilator, operatively driven by the circuit of embodiments. Based on suitable control from a control unit of the medical ventilator, a very fast and energy efficient control of breathing gases is provideable.
  • the valve thus has
  • the piezoactuator and valve may be of the type as described in US provisional patent applications of the same inventor with the following titles and application filing number "VALVE AND METHOD TO CONTROL A FLOW THROUGH THE VALVE"
  • the A method is a method 10 of controlling a capacitive element X, and comprises providing 110 a combined switched boost regulator circuit and a switched buck regulator circuit, and a plurality of change-over switches. Further, the method comprises providing 120 two operative states, wherein the first operative state is a boost regulator and the second operative state is a buck regulator.
  • said controlling comprises controlled switching 130 of at least four switches including a first primary switch SI and a second primary switch S2, which are arranged on a primary side, and a first secondary switch S3 and a second secondary switch S4, which are arranged on a secondary side.
  • the method further comprises obtaining 140 said operative states by opening or closing said first primary switch SI and said second primary switch S2 as well as said first secondary switch S3 and said second secondary switch S4 in different constellations .
  • the different constellations are detailed described above.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention pertains to a method of charging or discharging a capacitive element, preferably a piezoelectric crystal. The invention pertains also to a device which implements charging of a capacitive element according to said method. The device comprises a bipolar buck-boost converter, whereby a capacitive element can be charged with both positive and negative voltages. The discharge of the capacitive element is provided with energy recovery and feedback to the device's power supply.

Description

I LE: DRIVER CIRCUIT AND METHOD FOR CONTROLLING A CAPACITIVE ELEMENT
BACKGROUND OF THE INVENTION
Field of the Invention
The invention pertains to a drive circuit and a
procedure for controlling a capacitive element. More
precisely, the invention pertains to a Bipolar Buck-Boost Regulator for driving at least one piezoactuator.
Description of Prior Art
As new technological advances are made, above all in the field of piezoelectric ceramics, piezoactuators are increasingly replacing electromagnetic actuators. Piezo ceramic technology enables the manufacture of actuators with considerably faster response times and considerably lower energy consumption. However, the use of this technology brings with it other technological challenges. One of these is the electrical control of piezoactuators.
Piezoactuators require voltages of up to 1000V so that they can be actuated to their entire range. However, with modern ceramic multi-layer technology these voltages have been successfully brought down to the 100V range, a
considerable reduction, but still a high voltage to manage, especially from the electronics systems used today, which normally work at considerably lower voltages. The use of high voltages also involves risks for users of devices, especially in the field of medical applications.
In its construction, a piezoelectric actuator is very similar to a ceramic multilayer capacitor, and the combination of relatively large capacitance and high voltages provides for considerable amounts of energy being storable in these actuators. The advantage of this stored energy is that the actuator state is retained if the electrical connection is cut, and thus no energy is needed to maintain the state. However, the drawback is that stored energy must be dealt with if the actuator is to be controlled back to a lower movement amplitude. In linear control applications, this involves a great deal of this energy being lost for
generating heat. Yet another issue is that the piezo ceramic structure is subject to inherent friction, which means that piezoactuators are subject to mechanical hysteresis of approximately 20% magnitude. Therefore, in order not to lose motion, one can supply the actuator with a negative voltage of approximately 20% of the normal positive control voltage. The actuator should not be supplied with more negative voltages exceeding 20% of the maximum positive voltage, since this can destroy it.
One way of getting rid of many of the mentioned issues is by means of using a switching technique in combination with an inductor. The stored energy in the power supply unit can then be switched back to the actuator.
A number of solutions of this kind are, among other things, described in US patent 6,617,754, where switching is performed by a single inductor element against a high voltage source with a central outlet.
However, the disadvantage of this type of solution is that the device needs a double high voltage source with voltages in the range of 100V or more. The object of the invention is to provide a switched, energy recovery control of a capacitive element without using a high voltage source. Summary of the Invention
These objects are met by means of the device and the method in accordance with in the appended independent claims, while particular embodiments are dealt with in the dependent claims .
Accordingly, embodiments of the present invention seek primarily to mitigate, alleviate or eliminate one or more of the above-identified deficiencies or disadvantages in the art, singly or in any combination, and solves at least partly the abovementioned issues by providing a device and method according to the appended patent claims.
According to aspects of the invention, a device and a method are disclosed. This is achieved by means of a
capacitive element acting as a capacitor in the end stage of a boost regulator. By adding extra switch functions and by using an inductor with several windings the boost regulator can be combined with a buck regulator to provide charging of the capacitive element with energy recovery. Embodiments comprise a method of charging or discharging a capacitive element, preferably a piezoelectric crystal. A device charges a capacitive element according to this method.
According to the various embodiments, the device comprises a bipolar buck-boost converter, whereby a
capacitive element can be charged with both positive and negative voltages. The capacitive element is discharged with the abovementioned energy recovery and feedback to the device power supply according to certain embodiments. In the first aspect of the invention, a drive circuit is provided which is configured to control a capacitive element. The drive circuit comprises a combined switched boost regulator circuit and a switched buck regulator circuit, as well as a plurality of change-over switches. The drive circuit has two operative states which are selectable using the abovementioned change-over switches, wherein one operative state is a boost regulator and the other operative state is a buck regulator.
According to various embodiments, the abovementioned change-over switches comprises at least four switches, of which a first primary switch SI and a second primary switch S2 are arranged on a primary side and a first secondary switch S3 and a second secondary switch S4 are arranged on a secondary side.
In some embodiments, the drive circuit comprises at least one inductor which on the primary side preferably has at least two windings LI and L2.
The operative states may be obtained as follows:
by opening the second primary switch S2 and the first secondary switch S3 as well as connecting the second
secondary switch S4, thus providing a positive boost
converter which is controlled by the first primary switch SI for positive charging of the capacitive element X;
by opening the first primary switch SI and the second secondary switch S4 and connecting the first secondary switch S3, thus providing a negative boost converter which is controlled by the second primary switch S2 for negative charging of capacitive element X;
by opening the first primary switch SI and the second primary switch S2 and connecting the second secondary switch S4, thus providing a positive buck converter which is
controlled by the first secondary S3 for discharging of the capacitive element X and feedback to a tank capacitor C.
In another embodiment, the capacitive element X is earthed on one side, both the secondary switches S3 and S4 are placed on one side of the inductor's secondary winding L3, and a diode D2 is arranged between the second primary switch S2 and the primary inductor winding L2.
Clamping effects are avoided upon negative boosting by means of adding an extra diode D2, which results in that high negative voltages can be generated.
The circuit is built to drive capacitive elements, such as an actuator element, preferably a piezoactuator . The circuit is built with a boost regulator combined with a buck regulator by using an inductance/coil with more windings on the primary side and extra switches. Thanks to this
structure, the drive circuit can control the capacitive element by charging with either positive or negative voltages by switching the circuit to either a positive boost converter or a negative boost converter.
The capacitive element can also be discharged by switching the circuit to a positive buck converter, which discharges with energy recovery and feedback to the device power supply. This means that the energy accumulated in the actuator that would otherwise be lost as heat when an
actuator is controlled to a lower deflection is not lost.
Using this drive circuit structure, the negative control range to the actuator is also restricted. This means that when the drive circuit is used to control the actuator with a negative voltage, so as not to lose movement due to mechanical hysteresis, it is not possible to control the circuit at such high negative voltages that the actuator is destroyed. This limit on actuator capacity is in the range of 20% of the maximum permitted positive voltage.
The switches should preferably be MOS transistors, but are not limited to this.
In a second aspect, the invention comprises a method for driving and controlling capacitive elements. The method comprises providing a combined switched boost regulator circuit and a switched buck regulator circuit as well as a number of change-over switches, and providing two optional operative states by controlling these change-over switches, wherein one operative state is a boost regulator and the other a buck regulator.
In embodiments the boost regulator is used at negative and positive voltages to charge the capacitive element, such as an actuator element, preferably a piezoactuator, and the buck regulator is used to discharge the capacitive element by energy recovery and feedback to the drive circuit power supply .
In some embodiments a negative control range for the actuator is limited, such as limited to a range of 20% of the maximum permitted positive voltage.
The advantages of this method are the same as for the equipment described above. That is, that a capacitive
element, such as an actuator element, preferably a
piezoactuator, can be driven both with positive and negative voltages and be discharged without the energy accumulated in the actuator being lost, e.g. as heat, but can be recovered by feedback to the device power supply.
Further embodiments of the invention are defined in the dependent claims, wherein features for the second and subsequent aspects of the invention are as for the first aspect mutatis mutandis.
Brief Description of the Drawings
These and other aspects, features and advantages of which the invention at least is capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the
accompanying drawings, in which
Figure 1 shows a schematic view of an exemplary
embodiment of an electrical circuit;
Figure 2 shows a schematic view of an equivalent to the electrical circuit shown in Figure 1, connected as a positive boost converter;
Figure 3 shows a schematic view of an equivalent to the electrical circuit shown in Figure 1, connected as a negative boost converter;
Figure 4 shows a schematic view of an equivalent to the electrical circuit shown in Figure 1, connected as a positive buck converter;
Figure 5 shows a schematic view of yet another
exemplary embodiment of an electrical circuit; and
Fig. 6 is a flowchart of a method 10. Description of Embodiments
Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements.
Figure 1 shows a schematic view of an exemplary
embodiment of an electrical circuit.
The inductor has a winding ratio Nl and N2 on the primary side, and N3 on the secondary side.
Figure 2 shows a schematic view of an equivalent to the electrical circuit as shown in Figure 1, where S2 and S3 are open and S4 is closed. In this configuration the circuit is operative as a positive boost converter. Energy is switched by means of SI from Vcc and the tank capacitor C.
Figure 3 shows a schematic view of an equivalent to the electrical connection as shown in Figure 1, where SI and S4 are open and S3 is closed. In this configuration the
connection acts as a negative boost converter. Energy is switched with the help of S2 from Vcc and tank capacitor C. Diode Dl together with the inductor's winding ratio limits the controllable negative voltage to the capacitive element to the required fraction of Vcc.
Figure 4 shows a schematic view of an equivalent to the electrical circuit as shown in Figure 1, when SI and S2 are open and S4 is closed. In this configuration the circuit is operative as a positive buck converter. Energy is switched by means of S3 from the capacitive element X to the tank capacitor C.
Figure 5 shows a schematic view of yet another
exemplary embodiment of an electrical circuit according to a principle of the invention. In this exemplary embodiment, the capacitive element X is earthed on one side, and the switches S3 and S4 are arranged on one side of the inductor's
secondary winding L3. Furthermore, a diode D2 is added. D2 prevents the abovementioned clamping effect upon negative boost, which means that high negative voltages can be
generated when D2 is included in the circuit.
No connections for dealing with transients caused by shared inductance between the cooperating windings in the inductor are included in the abovementioned circuit examples. However, this is not shown here because it is a well known technology .
Description of Positive Boost
This process is active when a voltage Vcc is to be converted from a limited negative voltage to a high positive voltage across the crystal X. S2 and S3 are open, and S4 is closed in this operational state. The functional parts of the circuit in this operational state are described in Figure 2. Figure 2 shows a schematic view of this equivalent to the electrical circuit as shown in Figure 1, wherein S2 and S3 are open and S4 is closed.
1. When SI is closed, the current is ramped up in LI. The field in the transformer core builds up to a positive field value. During this time the voltage towards the diode D4 is Vcc*N3/Nl and there is no current flowing through D4 or X.
2. SI opens and the field in the transformer core drops towards zero. The voltage over D4 drops immediately until it starts to conduct, approx. -0.6V and a current flows through D4, L3 and X so that the voltage across X in a number of cycles is gradually ramped up to a high voltage of e.g. 120V. The voltage across Dl will rise across Vcc at each cycle, and no current flows through LI .
3. SI is connected again, and so on. Description of Negative Boost
This process is active when a voltage Vcc is to be converted from zero to a limited negative voltage across the crystal X. SI and S4 are open, and S3 is closed in this operational state. The functional parts of the circuit in this operational state are described in Figure 3. Figure 3 shows a schematic view of this equivalent to the electrical circuit as shown in Figure 1, wherein SI and S4 are open and S3 is closed.
1. When S2 is closed, the current is ramped up in L2. The field in the transformer core builds up to a negative field value. During this time the voltage towards diode Dl is Vcc and there is no current flowing through Dl . The voltage to diode D5 also becomes positive and no current flows through L3, D5 or X.
2. S2 opens and the field in the transformer core rises towards zero. There are then two competing processes:
A boost via L3 generates a negative voltage across X, or a boost across LI which ramps energy stored in the transformer back to C and supply voltage Vcc. The active boost process is determined by the voltage across the capacitive element (the piezo crystal) X, Vcc and the transformer ratio N3:N1. In practice this means that the negative boost is limited to
-Vcc*N3/Nl. If Vcc=12V and N3:N1 is 5:3, the maximum voltage across X is -20V. 3. S2 is closed again, and so on. Description of Positive Buck
This process is active when crystal X is to be
discharged, i.e. the voltage drops towards zero. SI and S2 are open, S4 is closed in this operational state. The
functional parts of the circuit in this operational state are described in Figure 4. Figure 4 shows a schematic view of this equivalent to the electrical circuit as shown in Figure 1, where SI and S2 are open and S4 is closed.
1. When S3 is closed, the current is ramped from X up in L3. The field in the transformer core builds up to a negative field value. During this time the voltage towards diode Dl is positive and there is no current flowing through Dl . The crystal X is gradually
discharged in this phase.
2. S3 opens and the field in the transformer core drops towards zero. The voltage across Dl immediately drops until it starts to conduct, approx. -0.6V and a current flows through Dl, LI and C so that energy from crystal X is fed back to C and Vcc.
3. S3 is connected again, and so on.
In case the capacitive element is a piezoactuator, it may very advantageously be controlled by the circuit of embodiments. The Bipolar Buck-Boost Regulator may be used for driving at least one piezoactuator.
The piezoactuator may be an actuator in a valve.
The valve may be a respiratory valve in a medical ventilator, operatively driven by the circuit of embodiments. Based on suitable control from a control unit of the medical ventilator, a very fast and energy efficient control of breathing gases is provideable. The valve thus has
considerably faster response times and considerably lower energy consumption than conventional valves in this field. The piezoactuator and valve may be of the type as described in US provisional patent applications of the same inventor with the following titles and application filing number "VALVE AND METHOD TO CONTROL A FLOW THROUGH THE VALVE"
US61/345, 623; "MECHANICAL AMPLIFIER, SYSTEM OF SAID
AMPLIFIERS AND METHOD FOR MECHANICALLY AMPLIFICATION OF A MOTION" US61/345, 625; "VALVE AND METHOD TO CONTROL A FLOW" US61/345, 628; and METHOD FOR CONTROLLING A HIGH-PRESSURE VALVE " US 61 /345 , 797 ; which are all incorporated herein by reference in their entirety for all purposes.
In Fig. 6 a flowchart of a method 10 is shown. The A method is a method 10 of controlling a capacitive element X, and comprises providing 110 a combined switched boost regulator circuit and a switched buck regulator circuit, and a plurality of change-over switches. Further, the method comprises providing 120 two operative states, wherein the first operative state is a boost regulator and the second operative state is a buck regulator. In the method, said controlling comprises controlled switching 130 of at least four switches including a first primary switch SI and a second primary switch S2, which are arranged on a primary side, and a first secondary switch S3 and a second secondary switch S4, which are arranged on a secondary side. The method further comprises obtaining 140 said operative states by opening or closing said first primary switch SI and said second primary switch S2 as well as said first secondary switch S3 and said second secondary switch S4 in different constellations . The different constellations are detailed described above.
The present invention has been described above with reference to specific embodiments. However, other embodiments than the above described are equally possible within the scope of the invention. The different features and steps of the invention may be combined in other combinations than those described. The scope of the invention is only limited by the appended patent claims.

Claims

A drive circuit configured to control a capacitive element (X) , comprising in combination a switched boost regulator circuit and a switched buck
regulator circuit, as well as a plurality of change¬ over switches, wherein the drive circuit has two operative states which are selectable by means of said change-over switches, wherein the first
operative state is a boost regulator and the second operative state is a buck regulator,
and wherein said change-over switches comprise at least four switches, of which a first primary switch (SI) and a second primary switch (S2) are arranged on a primary side and a first secondary switch (S3) and a second secondary switch (S4) are arranged on a secondary side; wherein the drive circuit comprises at least one inductor which on the primary side has at least two windings (LI and L2); and wherein said operative states are obtained by opening or closing said first primary switch (SI) and said second primary switch (S2) as well as said first secondary switch (S3) and said second secondary switch (S4) in different constellations.
The drive circuit according to claim 1, wherein said operative states are obtained as follows:
- by opening the second primary switch (S2) and the first secondary switch (S3) and connecting the second secondary switch (S4), a positive boost converter is provided which is controlled by the first primary switch (SI) for positive charging of the capacitive element (X) ;
- by opening the first primary switch (SI) and the second secondary switch (S4) and connecting the first secondary switch (S3) a negative boost
converter is provided, which is controlled by the second primary switch (S2) for negative charging of the capacitive element (X) ;
- by opening the first primary switch (SI) and the second primary switch (S2) and connecting the second secondary switch (S4), a positive buck converter is provided which is controlled by the first secondary (S3) for discharging of the capacitive element (X) and feedback to a tank capacitor (C) .
The drive circuit according to claim 2, wherein
- the capacitive element (X) is earthed on one side;
- both secondary switches (S3, S4) are placed on one side of the inductor's secondary winding (L3) ; and
- a diode (D2) is arranged between the second primary switch (S2) and the primary inductor winding (L2) .
The drive circuit according to claim 1, comprising and inductor having at least two windings as energy storage element for the drive circuit.
The drive circuit according to any of claims 1 to 4, wherein the drive circuit is configured to controllably supply positive voltages to the
capacitive element by controlling the switching of (SI) and (S2) .
The drive circuit according to any of claims 1 to 4, wherein the drive circuit is configured to controllably supply negative voltages to the
capacitive element using said first primary switch (SI) or said second primary switch (S2) .
7. The drive circuit according to claim 6, wherein a negative control range to the capacitive element is limited .
8. The drive circuit according to any of claims 1 to 7, wherein the capacitive element is an actuator element .
9. The drive circuit according to claim 8, wherein the actuator element is a piezoelectric actuator.
10. The drive circuit according to any of claims 1-9, wherein at least one of the change-over switches is a MOS transistor.
11. The drive circuit according to any of claims 1-10, operatively connected to a piezoelectric actuator of a valve.
12. The drive circuit of claim 11, wherein said valve is a valve in a medical ventilator.
13. A method (10) of controlling a capacitive element
(X), comprising providing (110) a combined switched boost regulator circuit and a switched buck
regulator circuit, and a plurality of change-over switches, and providing (120) two operative states, wherein the first operative state is a boost
regulator and the second operative state is a buck regulator, and wherein said controlling comprising controlled switching (130) of at least four switches including a first primary switch (SI) and a second primary switch (S2), being arranged on a primary side, and a first secondary switch (S3) and a second secondary switch (S4), being arranged on a secondary side; and obtaining (140) said operative states by opening or closing said first primary switch (SI) and said second primary switch (S2) as well as said first secondary switch (S3) and said second
secondary switch (S4) in different constellations.
14. The method according to claim 13, wherein the boost regulator is used for charging the capacitive element, such as an actuator element, preferably a piezoactuator, with positive voltages, and wherein the buck regulator is used for discharging the capacitive element with energy recovery and feedback to the power supply of the drive circuit; and wherein said controlling is performed by switching od said first primary switch (SI) or said second primary switch (S2) .
15. The method according to claim 13, wherein the boost regulator is used for charging the capacitive element, such as an actuator element, preferably a piezoactuator, with negative voltages, and wherein the buck regulator is used for discharging the capacitive element with energy recovery and feedback to the power supply of the drive circuit; and wherein said controlling is performed by switching od said first primary switch (SI) or said second primary switch (S2) .
16. The method according to claim 15, wherein a
negative control range to the actuator is limited, such as in the range of 20% of the maximum operative positive voltage.
17. The method according to any of claims 13-16, comprising said capacitive element (X) being a controllable piezoelectric actuator of a valve.
18. The method of claim 17, wherein said valve is valve in a medical ventilator.
EP11721479A 2010-05-17 2011-05-15 Driver circuit and method for controlling a capacitive element Withdrawn EP2572444A2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE1050485A SE536247C2 (en) 2010-05-17 2010-05-17 Drive circuit and method for controlling a capacitive element
US201061345764P 2010-05-18 2010-05-18
PCT/EP2011/057811 WO2011144542A2 (en) 2010-05-17 2011-05-15 Driver circuit and method for controlling a capacitive element

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EP2572444A2 true EP2572444A2 (en) 2013-03-27

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CN (1) CN102255556B (en)
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RU2698802C1 (en) * 2018-11-30 2019-08-30 Общество с ограниченной ответственностью "РЭНК" (ООО "РЭНК") Method for generation of mechanical oscillations and generator for its implementation

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US5691592A (en) * 1995-09-14 1997-11-25 Motorola, Inc. Actuator drive and energy recovery system
DE19825210C2 (en) 1998-04-23 2003-09-25 Gsg Elektronik Gmbh Circuit arrangement for dynamic control of ceramic solid state actuators
FR2829314B1 (en) * 2001-09-04 2004-08-27 Renault DEVICE FOR CONTROLLING A PIEZOELECTRIC ACTUATOR AND ITS IMPLEMENTING METHOD
FR2831727A1 (en) * 2001-10-30 2003-05-02 Renault CONTROL DEVICE FOR AN ELECTRONICALLY PILOT ULTRASONIC PIEZO-ELECTRIC ACTUATOR, AND ITS IMPLEMENTATION PROCESS
US7667371B2 (en) * 2007-09-17 2010-02-23 Motorola, Inc. Electronic device and circuit for providing tactile feedback
US7979727B2 (en) * 2007-12-28 2011-07-12 International Business Machines Corporation Apparatus, system, and method for an integrated power supply efficient in high and low power conditions

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Also Published As

Publication number Publication date
WO2011144542A3 (en) 2012-11-29
WO2011144542A2 (en) 2011-11-24
CN102255556B (en) 2016-08-31
CN102255556A (en) 2011-11-23
SE536247C2 (en) 2013-07-16
SE1050485A1 (en) 2011-11-18

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