Devices for supplying power from AC voltage

Abstract

The present specification relates to a device for supplying a voltage from an AC voltage, the device comprising: a capacitive element (120); two switches (132H, 132L) in a half-bridge configuration between terminals of the capacitive element (120); terminals (102, 104) for applying an AC voltage; a transformer (160) having a first winding (162) connecting one of the terminals (104) for applying the AC voltage to a junction node (136) between the switches (132H, 132L); and one or more circuits (170, 180, 140) configured to switch the switches (132H, 132L) to receive an AC current (I164) flowing through a second winding (164) of the transformer (160) and to adjust the voltage supplied by the device by affecting the frequency of the AC current and / or the phase shift of the AC current relative to when the AC current is received.

Description

[Technical Field]

[0001] TECHNICAL FIELD This disclosure relates generally to electronic circuits, and more particularly to devices that can be powered from an AC voltage. [Background technology]

[0002] Various devices are electrically powered by voltages different from the voltage of the power supply grid. For example, connected objects, mobile phones, digital tablets, and other portable electronic devices are equipped with power storage units such as batteries. Batteries are charged with a typical DC voltage of, for example, 5 V. This voltage may also be used to directly power devices. Power supply devices can derive this voltage from the AC voltage of the electrical network, typically at approximately 230 V (rms.) and 50 Hz or approximately 120 V (rms.) and 60 Hz. Summary of the Invention [Problem to be solved by the invention]

[0003] Embodiments overcome all or some of the disadvantages of known devices that are powered from an AC voltage.

[0004] Embodiments provide a power supply device that generates less heating than known devices for the same supplied power.

[0005] Embodiments provide a power supply device with a conversion efficiency higher than that of known devices.

[0006] Embodiments provide a particularly compact power supply device. [Means for solving the problem]

[0007] Accordingly, an embodiment provides a device for providing a DC voltage between two output terminals from an AC voltage applied to input terminals, the device comprising: a first capacitive element; and - two first switches of a half bridge between the terminals of the first capacitive element; - two second switches electrically connected in series between the terminals of the first capacitive element; a transformer having a first winding disposed between a junction node between the first switch and one of the input terminals; the other of the input terminals is coupled to a junction node between the second switches; a full-wave rectifier circuit for supplying a DC voltage, the full-wave rectifier circuit having two second capacitive elements electrically connected in series between the output terminals and two third switches each arranged between one of the output terminals and a second winding of the transformer; - a circuit configured to switch the first switch to control the second switch; a circuit configured to control the voltage supplied by the device, the circuit acting on the switching frequency and / or on the delay between the moment at which the AC current flowing through the second winding changes direction and the next moment of switching of the third switch; The device further comprises:

[0008] According to an embodiment, the device comprises: - a voltage sensor giving the value of the DC voltage; - circuitry configured to affect the switching frequency and / or the delay based on the value of the DC voltage; It is equipped with:

[0009] According to an embodiment, the device comprises a circuit configured to turn on one of the second switches in each half-wave of the AC voltage at least during a central phase of the half-wave, the one of the second switches being a function of the sign of the half-wave.

[0010] According to an embodiment, the device comprises a circuit configured to adjust the running average of the current flowing through the input terminal depending on a current setpoint by acting on the duty cycle of the switching of the first switch.

[0011] According to an embodiment, the current setpoint has a value representing the result of multiplying the value of the AC voltage by a conductance value.

[0012] According to an embodiment, the device comprises a circuit configured to adjust the value of the voltage of the first capacitive element by acting on the conductance value.

[0013] According to an embodiment, the device comprises, for at least one of the terminals of the first capacitive element, an additional capacitive element coupling one of the input terminals to the terminal of the first capacitive element.

[0014] According to an embodiment, the device comprises a circuit configured to shut off the second switch during a transition phase between the central phases.

[0015] According to an embodiment, the device comprises a circuit configured to gradually change the duty cycle of the switching of the first switch in each transition phase to obtain a predetermined voltage value on the second switch that is turned on during the central phase after the transition phase.

[0016] According to an embodiment, the central phase after each transition phase begins at a time when the AC voltage has the predetermined voltage value.

[0017] According to an embodiment, the transition phase after each central phase begins at a time when the AC voltage has the predetermined voltage value.

[0018] According to an embodiment, the device comprises a circuit configured to obtain zero voltage across each terminal of the first switches at the time of switching.

[0019] According to an embodiment, the transformer has a coupling coefficient less than one.

[0020] According to an embodiment, the first switch is a transistor of the HEMT type.

[0021] An embodiment provides a device powered by a USB-C connector, comprising a device as defined above. [Brief explanation of the drawings]

[0022] The foregoing and other features and advantages will be described in more detail in the following particular embodiments, given as non-limiting illustrations of the invention with reference to the accompanying drawings, in which:

[0023] [Figure 1] 1A and 1B show schematic diagrams of embodiments of devices powered by AC voltage. [Figure 2] 2 is a timing diagram illustrating the operation of the device of FIG. 1; [Figure 3] 1 shows a schematic and partial view of another embodiment of a device powered by an AC voltage. [Figure 4] 10 shows a partial schematic view of another embodiment of a device powered by an AC voltage. [Figure 5] 5 is a flowchart illustrating an example of a method performed by the device of FIG. 4. [Figure 6] 6 is a timing diagram illustrating the operation of the device of FIG. 4 when performing the method of FIG. 5. [Figure 7] FIG. 2 is a diagram illustrating an example of a full-wave rectifier circuit of the device of FIG. 1. [Figure 8] FIG. 2 is a diagram showing another example of a full-wave rectifier circuit of the device of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0024] Like features are indicated by like reference numerals in the various drawings, and in particular, structural and / or functional features common to various embodiments may have the same reference numerals and may have the same structural, dimensional, and material characteristics.

[0025] For clarity, only those steps and elements that are useful for understanding the embodiments described herein are shown and described in detail.

[0026] Unless otherwise specified, when referring to two elements connected together, this refers to a direct connection without any intermediate elements other than conductors, and when referring to two elements coupled together, this refers to the fact that the two elements may be connected or may be coupled through one or more other elements.

[0027] In the following disclosure, unless otherwise specified, when reference is made to terms that qualify absolute positions such as "front," "back," "top," "bottom," "left," "right," or relative positions such as "up," "down," "upper," "lower," or terms that qualify orientations such as "horizontal," "vertical," etc., this refers to the orientation of the drawing.

[0028] Unless otherwise specified, the terms "about," "approximately," "substantially," and "to the extent" refer to within 10%, preferably within 5%, of the relevant value.

[0029] FIG. 1 shows a schematic representation of an embodiment of a device 100 that draws power from an AC voltage of value Vin.

[0030] The AC voltage is the voltage of an electrical network and preferably has the voltage and frequency values ​​as described in the preamble. This is not limiting, as the AC voltage may have other voltage values, preferably a peak value of less than approximately 1.5 kV, and / or other frequencies, preferably less than approximately 1 kHz. For example, the voltage may be supplied by an on-board device, such as a vehicle alternator, or by an on-board power supply network.

[0031] An AC voltage is applied to nodes 102 and 104, which form the input terminals of device 100. If this AC input voltage is a network voltage having phase and neutral, two phase / neutral directions of application to nodes 102 and 104 are possible. Device 100 preferably comprises a voltage sensor (V) 105 associated, preferably connected, to nodes 102 and 104. Voltage sensor 105 provides a value Vin of the input voltage each time.

[0032] Device 100 provides a voltage between terminals 106 and 108 for powering an electronic device (not shown). Terminals 106 and 108 thus form output terminals of the device. Device 100 preferably includes a connector 110 that allows electrical connection to the electronic device to be powered. For example, connector 110 is a USB Type C ("Universal Serial Bus") connector, now referred to as a USB-C connector. Output terminals 106, 108 correspond to, for example, some of the pins of a USB-C connector. This example is not limiting, and the described embodiment is compatible with common connection modes to electronic devices.

[0033] The voltage supplied by device 100 is preferably a DC voltage, for example 5 V. In this way, the device forms an AC / DC converter. By way of example, the power supplied by device 100 may vary between zero and a maximum power during operation. The maximum power may be, for example, less than 500 W, preferably less than or equal to 100 W, and more preferably 100 W. This example is not limiting, and the device may supply other DC voltage levels.

[0034] The device 100 comprises a capacitive element 120 having two terminals 122H and 122L. The capacitive element 120 preferably comprises, e.g. is formed by, a capacitor or a collection of capacitors electrically connected in parallel and / or series between the terminals 122H and 122L.

[0035] Device 100 includes switches 130H and 130L in series between terminals 122H and 122L of capacitive element 120. Device 100 further includes switches 132H and 132L in series between terminals 122H and 122L of capacitive element 120. More precisely, terminal 122H is coupled, and preferably connected, to switches 130H and 132H. Terminal 122L is coupled, and preferably connected, to switches 130L and 132L. Node 134 couples, and preferably connects, switches 130L and 130H in series. Node 136 couples, and preferably connects, switches 132H and 132L in series.

[0036] The switches 130H, 130L, 132H, and 132L preferably include or are formed by transistors. The transistors are preferably field-effect, e.g., MOS, transistors. The channel type of the transistor is therefore typically determined by the sign of the voltage blocked by the transistor and the control signal applied to the transistor. The transistors forming the switches 130H, 130L, 132H, and 132L are more preferably high-electron-mobility transistor (HEMT) transistors, e.g., including gallium arsenide semiconductors. Such transistors have particularly high conductance in the on-state, enabling particularly high power efficiency. The transistors are preferably normally-off transistors, but may also be normally-on transistors. It is within the skill of a person skilled in the art to adapt the described embodiments to normally-on type transistors, for example as described in D. Bergogne et al., "Normally-On SiC JFETs in power converters: Gate driver and safe operation," 2010 6th International Conference on Integrated Power Electronics Systems, Nuremberg, 2010, pp. 1-6.

[0037] The switches 130H and 130L are controlled, for example, by a control circuit 138 (DRV). According to an embodiment, the control circuit 138 receives an AC voltage value Vin. Therefore, the control circuit 138 is configured such that when the potential of the node 102 is greater than the potential of the node 104, i.e., when the AC voltage between the nodes 104 and 102 is in a positive half-wave, the switch 130H is conductive (on) and the switch 130L is non-conductive (off). Similarly, when the potential of the node 102 is less than the potential of the node 104, i.e., when the AC voltage between the nodes 104 and 102 is in a negative half-wave, the switch 130L is on and the switch 130H is off. This is not limiting; the signs of the half-waves may be reversed, and / or the switches 130H and 130L may be controlled according to other embodiments, such as those described below in connection with FIGS. 3-5.

[0038] The switches 132H and 132L are controlled by a control circuit 140 (DRV). During operation, the control circuit 140 can alternately turn on the switches 132H and 132L. The switches that are not turned on are off. In other words, the switches 132H and 132L are switched in opposite directions. In this way, the switches form a controlled half-bridge. Each switch corresponds to a transition from a state in which one switch of the half-bridge is on to a state in which the other switch of the half-bridge is on. Each switching step specifically prevents two switches of the half-bridge from being turned on simultaneously during switching. For example, to facilitate these steps, each switch of the half-bridge may be a transistor having a diode with an anode formed by the transistor's source and a cathode formed by the transistor's drain. The described embodiment is compatible with the normal switching steps of a controlled half-bridge.

[0039] Thus, each switch 132H, 132L is successively switched from an on state to an off state. This series of states or cycles is repeated at a frequency f, referred to as the switching frequency. The on / off state of switch 132H is controlled by a duty ratio α, which is determined for each cycle by the ratio of the duration of the on state of switch 132H to the overall duration of the cycle. The switching frequency and duty ratio are received, for example, by control circuit 140. Non-limiting examples of circuits for providing duty ratio α are described below in connection with FIGS. 3-6. Alternatively, the duty ratio is determined by the ratio of the duration of the on state of switch 132L to the overall duration of the cycle.

[0040] The switching frequency f is in a range of switching frequencies higher than the frequency of the AC voltage, for example 10 times higher, preferably 100 times higher, more preferably 1,000 times higher than the frequency of the AC voltage. For example, the switching frequency range is between 50 kHz and 10 MHz, preferably between 100 kHz and 3 MHz.

[0041] One of the nodes to which the AC voltage is applied (node ​​102) is coupled, and preferably connected, to node 134. A current sensor 150 (I) is preferably provided at the junction between node 102 and node 134. Current sensor 150 continuously provides the value of the current Iin entering device 100 through node 102. The junction between node 102 and node 134, even with current sensor 150 present, preferably has a resistance of less than 10 mΩ, and more preferably less than 5 mΩ.

[0042] The other node (node ​​104) to which the AC voltage is applied is coupled, and preferably connected, to node 136 by a winding 162 of a transformer 160. In other words, winding 162 is disposed between node 104 and node 136. Transformer 160 further includes another winding 164. In a variant, current sensor 150 is disposed between node 104 and transformer 160 or between transformer 160 and node 136, instead of between node 102 and node 134.

[0043] Transformer 160 has a leakage inductance between winding 162 and winding 164 that corresponds to a coupling coefficient of the transformer that is less than 1. Preferably, transformer 160 has a coupling coefficient between winding 162 and winding 164 that is less than 1, for example, between 0.8 and 0.98. Transformer 160 has such a coupling coefficient for at least one frequency in the range of switching frequencies, for example, for all values ​​in the range of switching frequencies. The effect of the coupling coefficient may be achieved by adding an external inductance in series.

[0044] Device 100 further includes circuitry 170 coupled, preferably connected, across winding 164. Circuitry 170 is coupled, preferably connected, to terminals 106 and 108. Circuitry 170 is configured to provide the voltage provided by device 100 between terminals 106 and 108.

[0045] According to a preferred embodiment, circuit 170 comprises two capacitive elements 172H, 172L coupled, preferably connected, in series between output terminal 106 and output terminal 108. Node 173 thus couples, preferably connects, capacitive elements 172H and 172L in series. Capacitive elements 172H, 172L may each comprise or be formed by a capacitor or a plurality of capacitors connected in series and / or parallel.

[0046] Circuit 170 preferably includes two switches 174H, 174L electrically coupled, preferably connected, in series between output terminal 106 and output terminal 108. Switches 174H, 174L are preferably transistors. Thus, node 175 electrically couples, preferably connects, switches 174H and 174L in series. Switches 174H, 174L are controlled, for example, by a control circuit 176 (DRV) included in circuit 170. Switches 174H and 174L form a controlled half-bridge. Winding 164 couples, preferably connects, nodes 173 and 175 together. Thus, switches 174H, 174L couple, preferably connects, terminals 106, 108, respectively, to winding 164. In other words, switches 174H, 174L are disposed between respective terminals 106, 108 and winding 164.

[0047] During operation, switching switches 132H, 132L causes current I164 to alternately flow in both directions through winding 164 at switching frequency f. For example, the switching times of switches 174H, 174L are determined by control circuit 176, for example, based on the value of current I164 (sensor 177) and / or based on a synchronization signal 178 related to the switching frequency (e.g., originating from control circuit 140). For example, when current I164 flows from node 173 to node 175, switch 174H is turned on and switch 174L is turned off, charging capacitive element 172H. When current I164 flows from node 175 to node 173, switch 174L is turned on and switch 174H is turned off, charging capacitive element 172L. Thus, when circuit 170 receives AC current flowing through winding 164 of transformer 160, each capacitive element receives current flowing in one of two directions, generating a positive DC voltage between output terminals 106 and 108 of connector 110.

[0048] Thus, circuit 170 receives current flowing in both directions through winding 164 and provides a DC output voltage based on this current. Circuit 170 therefore forms a full-wave rectifier circuit that provides a DC voltage. The above-described preferred embodiment of circuit 170 is not limiting, and circuit 170 may be replaced with any circuit adapted to receive current flowing through winding 164, preferably in both directions. Such a circuit preferably includes two capacitive elements, each arranged to receive current flowing in one of two directions. Preferably, current can flow in one or the other of two directions by turning on one or the other of two switches.

[0049] Transformer 160 may have multiple windings instead of winding 164. Circuit 170 may therefore be replaced by any full-wave rectifier circuit adapted to receive one or more currents flowing through those windings. Preferably, this or these currents can be caused to flow by turning on a switch. Examples of such circuits that can replace circuit 170 are described below in connection with Figures 7 and 8.

[0050] Additionally, although a transformer having only two windings and one circuit for receiving current through the transformer is described herein, a transformer having three or more windings may be provided. Thus, multiple circuits for receiving current through the windings of the transformer may be provided. Alternatively, the transformer may be replaced with multiple transformers having windings in series between node 104 and node 136.

[0051] The device 100 further comprises a circuit 180 (CTRL). The circuit 180 receives the value Vs of the output voltage provided by the device 100 between the output terminals 106 and 108. The value Vs is provided, for example, by a voltage sensor 182 (V) connected to the terminals 106 and 108. The circuit 180 controls the output voltage. The circuit 180 is preferably capable of adjusting or regulating the output voltage, i.e., making the value Vs of the output voltage equal to a set value Vref. The set value Vref is preferably constant, i.e., corresponds to a DC output voltage of, for example, 5 V. This is not a limitation, as the set value Vref may vary over time.

[0052] According to the embodiment, the circuit 180 acts on the frequency of the AC current I164, i.e., the switching frequency f of the half-bridge of the switches 132H and 132L, to make the voltage value Vs equal to the set value Vref. If the value Vs is smaller than the set value Vref, the frequency f is decreased. This increases the value of the output voltage Vs, as will be shown below in connection with FIG. 2. Similarly, if the value Vs is greater than the set value Vref, the frequency f is increased. This decreases the value of the output voltage Vs. The frequency f thus serves as a regulation variable, acting on the regulation variable to adjust the value Vs according to the set value. The method for deriving the regulation variable from the value to be regulated and the set value is not described in detail herein, and the described embodiment is compatible with conventional methods for deriving a regulation variable from the value to be regulated and the set value.

[0053] According to the embodiment, in order to make the voltage value Vs equal to the set value Vref, the circuit 180 acts on a phase shift D between the AC current I164 and the cycle of bidirectionally receiving this current. In other words, the switching cycles of the switches 174H and 174L are phase-shifted relative to the bidirectional switching of the AC current I164. The phase shift D corresponds to the delay between the moment when the current I164 changes direction and the next moment when the switches 174H and 174L switch. If the value Vs is greater than the set value Vref, the phase shift D is increased. This reduces the value of the output voltage Vs, as will be shown below in connection with FIG. 2. Similarly, if the value Vs is less than the set value Vref, the phase shift D is decreased, resulting in an increase in the value of the output voltage Vs. The phase shift D therefore functions as a regulation variable, acting on the regulation variable to adjust the value Vs according to the set value.

[0054] Alternatively, circuit 180 provides two phase shift values. One phase shift value corresponds to the delay between when switch 174L turns on and when switch 174H turns off relative to when current I164 begins to flow from node 173 to node 175. The other phase shift value corresponds to the delay between when switch 174H turns on and when switch 174L turns off relative to when current I164 begins to flow from node 175 to node 173.

[0055] Thus, the circuit 180 preferably adjusts the value Vs of the output voltage relative to a set value Vref by acting on the frequency f and / or the phase shift D. More preferably, the circuit 180 acts on the frequency f and the phase shift D simultaneously or sequentially to adjust the value Vs of the output voltage relative to the set value Vref. Alternatively, the circuit 180 controls the value Vs without adjusting the value Vs. In this variant, the values ​​of the frequency f and the phase shift D corresponding to the desired voltage value Vs are predetermined depending on various operating parameters, such as the supply current, the values ​​of the voltage and / or current received by the device 100, etc.

[0056] It is preferable to select a frequency threshold, e.g., the upper limit of the switching frequency range, and a phase shift threshold, e.g., zero phase shift. In the first operating mode, circuit 180 acts on frequency f by maintaining a phase shift D equal to the phase shift threshold as long as frequency f remains below the frequency threshold. If frequency f reaches the frequency threshold, circuit 180 switches to the second operating mode. In the second operating mode, circuit 180 acts on phase shift D by maintaining frequency f equal to the frequency threshold as long as phase shift D remains greater than the phase shift threshold. If phase shift D reaches the phase shift threshold, circuit 180 switches to the first operating mode.

[0057] To obtain a regulated voltage from an AC voltage, it is possible to provide an input stage that allows the AC voltage to be fed into a power storage unit, such as a capacitor, and then an output stage that converts the voltage of the power storage unit into a regulated output voltage.

[0058] Compared to such devices with a power storage between the two stages, device 100 has fewer switches and is more power efficient. The fewer switches allows for a more compact device with the same supplied power. The higher power efficiency allows for power savings and less heating during operation.

[0059] Device 100 is preferably placed in a non-ventilated wall outlet. Increased compactness and reduced heating during operation facilitate the formation of non-ventilated wall outlets with devices such as device 100.

[0060] Preferably, device 100 further comprises circuitry (not shown) configured to obtain zero voltage across each of switches 132H and 132L at the time of switching. Such an operating mode of the half-bridge of switches is referred to as a ZVS "zero voltage switching" type. The described embodiment is compatible with conventional ZVS type switching circuits, which allows for reduced component size and / or increased efficiency and / or a higher upper limit for the switching frequency range.

[0061] Figure 2 is a timing diagram that illustrates the operation of the device of Figure 1. More precisely, Figure 2 shows the shape of the control signal S132 for switch 132H, the current I164 in winding 164, the signal S174 for controlling switch 174H, and the power P170 received by circuit 170 (here, capacitive elements 172H and 172L). Current I164 is represented by an algebraic value, with positive values ​​corresponding to the flow direction from node 173 to node 175 and negative values ​​corresponding to the other direction.

[0062] Two switching cycles of switches 132L and 132H are shown. The voltages on capacitive elements 120, 172H, and 172L and the AC input voltage do not have time to change significantly during these two cycles. The example shown is performed during the positive half-wave of the input voltage (while the potential at node 102 is higher than the potential at node 104) with a duty ratio α of approximately 0.5.

[0063] Signal S132 is initially high, so switch 132H is on and switch 132L is off, causing current I164 to increase. By selecting a transformer coupling coefficient less than 1, the leakage inductance caused by this coupling coefficient can limit the rate at which current I164 increases.

[0064] The initially negative current I164 becomes zero at time t0. At time t1, after a delay corresponding to the phase shift D, the initially low signal S174 switches to a high state. Thus, switch 174H is turned on and switch 174L is turned off. From time t1, the current I164 increases more slowly than between time t0 and time t1. From time t1, the circuit 170 receives power and this received power P170 increases.

[0065] At time t2, signal S132 switches to a low level. Therefore, switch 132H switches to an off state, and switch 132L switches on. From this time t2, the current I164, which has reached its maximum value, and the received power P170 decrease. The lower the frequency f, the longer the time for the current I170 to increase, and the higher the maximum value reached by the current. In other words, the lower the frequency f, the lower the impedance associated with the leakage inductance, which increases the current I164. Therefore, the maximum value of the received power increases. Therefore, when the frequency f decreases, the value of the output voltage Vs increases. Similarly, when the frequency f increases, the value of the output voltage Vs decreases.

[0066] At time t3, current I 164 becomes zero. After time t3, switch 174H and switch 174L remain on and off, respectively, until a delay corresponding to phase shift D has elapsed. The direction of the current reverses, i.e., capacitive element 172H discharges. This corresponds to the power being fed back into transformer 160 by circuit 170. Power P 170 then takes on a negative algebraic value 210. The greater the phase shift D, the more power is fed back by circuit 170. This causes the value of output voltage Vs to decrease. Similarly, if phase shift D decreases, the output voltage increases.

[0067] FIG. 3 shows, partially and schematically, an embodiment of a device 300 that draws power from an AC voltage of value Vin.

[0068] Device 300 comprises the same elements as device 100 of FIG. 1, which are arranged identically or similarly. These elements will not be described again here. Circuits 138, 140, 176, and 180 are not shown in FIG. 3. Device 300 corresponds to device 100 with additional elements added. More precisely, these additional elements form an example of a circuit adapted to generate a value for the duty ratio α of the switching of switches 132H and 132L.

[0069] The device 300 comprises a circuit 310 (CTRL) that receives the value of the input current Iin provided by the current sensor 150. The circuit 310 provides the duty ratio α. More precisely, the circuit 310 is configured to make the average value of the value Iin during each switching cycle of the switches 132H and 132L, i.e., the moving average or sliding average of the value Iin, equal to the current set value Iref. For example, the moving average is obtained by filtering the value Iin, for example, by a low-pass filter having a cutoff frequency lower than the frequency f.

[0070] The circuit 310 acts on the duty cycle α to make the moving average of the value Iin equal to the set value Iref. In other words, the circuit 310 uses the duty cycle α as a regulation variable to adjust the input current according to the set value Iref.

[0071] The set value Iref preferably corresponds to the result of multiplication (by the multiplication circuit 320) of the AC input voltage value Vin and the conductance value G (Iref=G×Vin). Therefore, the value Iin of the current entering through the node 102, i.e., the current supplied by the electrical network, for example, is proportional to the AC voltage. This makes it possible to avoid various reactive power generation in the electrical network. This makes it easy to manufacture the device 300 in accordance with various standards regarding the harmonic levels of the current consumed in the electrical network, such as the EN 61000-3-2 standard.

[0072] The device preferably further comprises a circuit 330 (MAX) coupled, for example connected, to the terminals 122H and 122L of the capacitive element 120. By way of example, the circuit 330 provides a maximum value VM of the voltage between the terminals 122H and 122L reached during each half-wave of the AC input voltage. The maximum value VM is received by a circuit 340 (CTRL) that provides a conductance value G. The circuit 340 is configured to act on the conductance value G to make the maximum value VM equal to the set value VCref. In other words, the circuit 340 uses the conductance G as an adjustment variable to adjust the charging of the capacitive element 120 in response to the set value Iref. The circuit 340 is compatible with known methods for deriving the adjustment variable from the value to be adjusted and the set value. As a specific example, the value adjusted by circuit 340 has a maximum value VM, but the value adjusted by circuit 340 may be any value representing the voltage of capacitive element 120, or any value having a variation related to the variation of this voltage level.

[0073] 1 and 3, separate circuits 138, 140, 176, 180, 310, 320, 330, 340, i.e., collections of circuits, are described. According to other embodiments, all or part of these circuits are replaced with digital circuits having a memory and a processing unit, such as a microprocessor, that are configured to perform the functions of the circuits they replace, i.e., the memory contains a program that, when executed by the processing unit, causes the above-mentioned functions to be performed.

[0074] FIG. 4 partially and schematically illustrates an embodiment of a device 400 that is powered from an AC voltage.

[0075] Device 400 comprises elements identical or similar to those of device 100 of Figure 1, which are identically or similarly arranged and these elements will not be described in detail again.

[0076] The device 400 comprises a circuit 410 (CTRL) having a memory 412 (MEM) and a processing unit 414 (CPU). Preferably, all or some of the functions of the circuits 138, 140, 176, 180 described in relation to Figure 1 are performed by the circuit 410. More preferably, all or some of the functions of the circuits 138, 140, 176, 180 described above in relation to Figure 3 are also performed by the circuit 410.

[0077] Preferably, device 400 further comprises a capacitive element 420 linking, preferably connecting, terminal 104 and terminal 122L. Alternatively, device 400 comprises a capacitive element 422 (shown by a dotted line) linking, preferably connecting, terminal 104 and terminal 122H. More preferably, device 400 comprises both capacitive element 420 and capacitive element 422. Capacitive element 420 and / or capacitive element 422 may comprise or be formed by a capacitor or capacitors electrically connected in series and / or parallel.

[0078] The device 400 further comprises a voltage sensor 430 providing a value V420 of the voltage across the capacitive element 420, and a voltage sensor 332 providing a value V120 of the voltage across the capacitive element 120. Alternatively, the voltage sensor 332 is replaced by a sensor of the voltage across the capacitive element 422.

[0079] Figure 5 illustrates an example of a method performed by device 400 of Figure 4. More precisely, the method of Figure 5 is performed when a program contained in memory 412 is executed by processing unit 414. Figure 6 is a timing diagram illustrating the operation of device 400 when performing the method of Figure 5. More precisely, Figure 6 illustrates the value of the AC input voltage Vin, the voltage V120 of capacitive element 120, the voltage V130H of switch 130H, the voltage V130L of switch 130L, and the algebraic value Iin of the current entering through input terminal 102 during two consecutive opposite positive and negative half-waves of the AC input voltage.

[0080] The AC input voltage successively assumes relatively low absolute values ​​(at the beginning and end of each half-wave) and relatively high absolute values ​​(midway through each half-wave). Capacitive element 120 receives power when the AC voltage is high and returns this power when the AC voltage is low. To enable capacitive element 120 to perform this role, a capacitance value greater than 100 nF and less than 100 μF, for example, and preferably less than 10 μF, is selected for capacitive element 120.

[0081] From the storage and extraction phases, the voltage across the capacitive element 120 varies at twice the frequency of the AC voltage Vin. The voltage varies between a minimum value Vmin and a maximum value VM.

[0082] The difference between the maximum and minimum values ​​corresponds to the amplitude change in the voltage of the capacitive element 120. This amplitude may be increased relative to the amplitude of the storage element of the power storage device between the two stages described above, and too strong a change in the power storage voltage can cause problems with the operation of the second stage. The capacitance value of the capacitive element 120 is preferably selected so that the amplitude of the voltage change exceeds 10% of the maximum value VM when the device operates at maximum power. For example, this capacitance value is less than 100 μF, preferably less than 10 μF. Therefore, the capacitive element 120 may be formed of one or more ceramic-type capacitors, which can improve the lifespan and efficiency compared to chemical capacitors.

[0083] During the operation phase 610, which is in the center portion of the positive half-wave, switch 130H is in the ON state and switch 130L is in the OFF state. The method has two steps 510 and 512 during the operation phase 610.

[0084] In step 510 (control Iin), the value of the duty ratio α is acted upon to obtain a current Iin equal to the set value Iref (equal to G×Vin) on average over each switching cycle of the switches 132H and 132L. This corresponds to the function of the circuit 310 in FIG. 3.

[0085] In step 512 (|Vin| < Vth?), the value Vin of the AC input voltage is compared with the voltage threshold Vth. If the value Vin is greater than the voltage threshold Vth (N), the method returns to step 510. Otherwise, the method proceeds to step 520 (cut off) to end the operation phase 610.

[0086] As a variant, steps 510 and 512 are executed in parallel until the value Vin is less than the voltage threshold Vth in step 512.

[0087] The conductance value G does not change significantly during two consecutive half - waves. Therefore, during phase 610, the values Iin and Vin are proportional. In the situation of a sinusoidal AC voltage shown, the input current is in phase with the input voltage and follows the sinusoidal part.

[0088] The operation phase 620 starts from step 520. In this step 520, both switch 130H and switch 130L are turned off. Therefore, the input terminal 102 is disconnected and the current Iin remains zero throughout the phase 620.

[0089] As an example, the method has two consecutive steps 530 and 532 during phase 620.

[0090] During step 530 (while tilting α), the duty ratio is gradually set to a predetermined value, that is, the duty ratio is set to a predetermined value within a time range longer than the switching cycle time of switches 132H and 132L, for example, more than 10 times longer. More preferably, the duty ratio is set to a predetermined value within a time range longer than 10% of the duration of operation phase 620 in addition to half of the duration of operation phase 620.

[0091] During step 532 (waiting until Vin = VL), the duty cycle is maintained at a predetermined duty cycle value and waits until voltages Vin and V130L are equal or substantially equal. Voltage V130L corresponds to the value V420 of the voltage across capacitive element 420. After this step, the method proceeds to step 540 (connect L), which ends stage 620.

[0092] In step 540, switch 130L is turned on. Switch 130H remains off. Waiting until voltages Vin and V130L are substantially equal allows switch 130H to reduce the charging or discharging current of capacitive element 420 to approximately zero at the time switch 130H is turned on, thereby avoiding various problems of efficiency and / or damage to device components.

[0093] Step 540 marks the start of an operational phase 630, which is similar or identical to operational phase 610, except that switch 130L is on and switch 130H is off. Operational phase 630 includes steps 550 and 552, which are similar or identical to steps 510 and 512, respectively. Operational phase 630 ends with step 560 (disconnect), which is similar or identical to step 520.

[0094] Operational phase 640 begins with step 560, which turns off switches 130H and 130L. As during phase 620, current Iin is zero. As with phase 620, phase 640 has two steps, 570 and 572. Step 570 (ramp α) is the same as or similar to step 530.

[0095] During step 572 (waiting for Vin = VH), the duty cycle is maintained at a predetermined duty cycle value until the AC voltage Vin and the voltage V130H across switch 130H are equal or substantially equal, where V130H corresponds to the difference between the voltage values ​​V120 and V420.

[0096] After step 572, the method proceeds to step 580 (Connect H), which ends stage 640 and begins a new stage 610. In step 580, switch 130L is turned on. Switch 130H remains off.

[0097] 3, the function of circuit 310, i.e., the function of influencing the duty cycle to obtain a value of input current Iin equal to a set value, is limited to only steps 610 and 630. Steps 610 and 630, which are located in the middle of each half-wave, alternate with transition steps in which AC current Iin becomes zero. This makes it possible to avoid operating modes in which the duty cycle approaches either the value 0 or the value 1. Therefore, the switching of switches 132H and 132L in devices 400 of FIGS. 4, 5, and 6 is simpler than in device 300 of FIG. 3.

[0098] The predetermined value of the duty ratio reached during step 532 is preferably selected so that the voltage across switch 130L (i.e., voltage V420) at step 540 has a predetermined voltage value. The predetermined value of the duty ratio reached during step 572 is preferably selected so that the voltage across switch 130H (i.e., voltage V420) at step 580 has the same predetermined voltage value in absolute value.

[0099] In the above example, stages 620 and 640 each comprise two separate steps, but these two steps may be replaced with any step that allows the respective voltages V130L, V130H to reach a predetermined voltage value at the end of the stage.

[0100] The predetermined value common to step 532 and step 572 is equal to the voltage threshold Vth that determines the initiation of steps 620 and 640, so that it is possible to obtain periods 620 that are symmetrical with respect to when AC voltage Vin becomes zero, respectively, thereby reducing even-order harmonics in current Iin.

[0101] The predetermined voltage value and voltage threshold Vth common to steps 532 and 572 are preferably selected so that steps 620 and 640 are sufficiently short so that the harmonic levels of the current comply with standards such as the EN 61000-3-2 standard mentioned above.

[0102] FIG. 7 shows an example of a full-wave rectifier circuit 770 that can replace circuit 170 of the device of FIG. 1 when transformer 160 has two windings 764H and 764L electrically connected in series between two terminals 780H and 780L instead of winding 164 (FIG. 1).

[0103] Circuit 770 has elements that are the same as or similar to the elements of circuit 170 of Figure 1, which are arranged in the same or similar manner. These elements will not be described in detail again; only the differences are highlighted.

[0104] Circuit 770 of FIG. 7 differs from circuit 170 of FIG. 1 in the following ways. Switch 174H and switch 174L (FIG. 1) are replaced by switch 774H, which couples, preferably connects, terminal 780H to output terminal 106, and switch 774L, which couples, preferably connects terminal 780L to output terminal 108. The junction node 173 of the capacitive element 172H and the capacitive element 172L is coupled, preferably connected, to the junction node 782 of the winding 764H and the winding 764L.

[0105] In the variant shown in dotted lines, circuit 770 further includes a switch 774L' which couples terminal 780H to output terminal 108, and preferably a switch 774H' which couples terminal 780L to output terminal 106.

[0106] In operation, switches 774H and 774L are controlled the same as or similar to the controls described above for switches 174H and 174L.

[0107] Figure 8 also shows another example of a full-wave rectifier circuit 870 that can replace circuit 170 of the device of Figure 1 when transformer 160 has two windings 864H and 864L instead of winding 164 (Figure 1). Winding 864H has terminals 880H and 880H', and winding 864L has terminals 880L and 880L'.

[0108] Circuit 870 has elements that are the same as or similar to the elements of circuit 170 of Figure 1, which are arranged in the same or similar manner. These elements will not be described in detail again; only the differences are emphasized.

[0109] Circuit 870 differs from circuit 170 of FIG. 1 in the following ways: Switch 174H and switch 174L (FIG. 1) a switch 874H that couples, preferably connects, terminal 880H to output terminal 106, and a switch 874L that couples, preferably connects, terminal 880L to output terminal 108; a switch 874H' that couples, preferably connects, terminal 880H' to output terminal 106, and a switch 874L' that couples, preferably connects, terminal 880L' to output terminal 108; a switch 875H that couples, preferably connects, terminal 880H to node 173, and a switch 875L that couples, preferably connects, terminal 880L to node 173; and a switch 875H' that couples, preferably connects, terminal 880H' to node 173, and a switch 875L' that couples, preferably connects, terminal 880L' to node 173; has been replaced with.

[0110] In operation, switches 874H and 874L, and switches 874H' and 874L' are controlled in the same or similar manner as described above for switches 174H and 174L.

[0111] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations can be combined, and other variations will occur to those skilled in the art. In particular, each of the above-described values ​​provided by sensors such as sensor 105, sensor 150, sensor 182, and sensor 430 or circuits such as circuit 138, circuit 140, circuit 170, circuit 180, circuit 310, circuit 320, circuit 330, circuit 340, or circuit 410 may be replaced with any value representing the above-described value.

[0112] Finally, the actual implementation of the embodiments and variations described herein is within the skill of those skilled in the art based on the functional representations set forth above.

[0113] This patent application claims priority from French Patent Application No. 19 / 06463, which is incorporated herein by reference.

Claims

1. 1. A device for providing a DC voltage between two output terminals from an AC voltage applied to its input terminals, comprising: a first capacitive element; two first switches of a half-bridge between the terminals of said first capacitive element; two second switches electrically connected in series between the terminals of said first capacitive element; a transformer having a first winding arranged between a junction node between said first switches and one of said input terminals; the other of the input terminals is coupled to a junction node between the second switches; a full-wave rectifier circuit for supplying a DC voltage, the full-wave rectifier circuit comprising two second capacitive elements electrically connected in series between the output terminals and two third switches each arranged between one of the output terminals and a second winding of the transformer; a circuit configured to switch said first switch at a switching frequency and to control said second switch depending on the value of said AC voltage; a circuit configured to control the DC voltage supplied by the device, said circuit acting on the switching frequency and / or on the delay between the moment at which the AC current flowing through the second winding changes direction and the next moment of switching of the third switch; an additional capacitive element for at least one of the terminals of the first capacitive element, coupling one of the input terminals to the terminal of the first capacitive element; a circuit configured to turn on one of the second switches during at least a center phase of each half-wave of the AC voltage; wherein one of the second switches is a function of the sign of the half-wave; a circuit configured to turn off the second switch during a transition phase between center phases of half waves of the AC voltage; The device further comprises:

2. a voltage sensor giving the value of a DC voltage; a control circuit configured to affect the switching frequency and / or the delay depending on the value of the DC voltage; The device of claim 1 , comprising:

3. 3. The device according to claim 1, further comprising a circuit configured to adjust the running average of the current flowing through the input terminal depending on a current setpoint by acting on the duty cycle of the switching of the first switch.

4. The device of claim 3 , wherein the current setpoint has a value representing the product of the AC voltage value multiplied by a conductance value.

5. 5. The device of claim 4, comprising a circuit configured to adjust the value of the voltage across the first capacitive element by acting on the conductance value.

6. 6. The device according to claim 1, further comprising a control circuit configured to gradually vary the duty cycle of the switching of the first switch in each of the transition phases to obtain a predetermined voltage value on the second switch that is turned on during the central phase after the transition phase.

7. 7. The device of claim 6, wherein the central stage after each of the transition stages begins at a time when the AC voltage has the predetermined voltage value.

8. 8. The device of claim 6 or 7, wherein the transition phase after each of the central phases begins at a time when the AC voltage has the predetermined voltage value.

9. A device according to any one of the preceding claims, comprising a control circuit configured to obtain zero voltage across each terminal of the first switches at the time of switching.

10. The device according to any one of claims 1 to 9, wherein the transformer has a coupling coefficient less than 1.

11. The device according to any one of claims 1 to 10, wherein the first switch is a transistor of the HEMT type.

12. The device according to any one of claims 1 to 11, wherein the transformer has a leakage inductance.

13. A device powered by a USB-C connector, comprising a device according to any one of claims 1 to 12.

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