Operating mode for a synchronous converter

Abstract

A mechanism for defining an operating mode of a control device for a synchronous converter device. The control device is configured to control activation and deactivation of switches in an inverter of the synchronous converter device. The control device operates in at least one of three different operating modes in response to power to be output by the synchronous converter device or power to be provided.

Description

Technical Field

[0001] This invention relates to the field of synchronous converters, and more particularly to the operating modes of synchronous converters. Background Technology

[0002] Synchronous converters, such as synchronous buck or boost converters, are becoming increasingly popular because they can drive loads with variable power demands, such as dimmable LED loads. Furthermore, recent advancements in transistors, such as the production of GaN or SiC transistors, have enabled the miniaturization and high efficiency of synchronous buck or boost converters.

[0003] Synchronous converters are typically associated with a maximum load rating, which is the maximum power rating of a load from which power can be drawn. An ideal synchronous converter can efficiently power loads with power ratings between zero (or negligible) and the maximum load rating. In other words, an ideal synchronous converter can provide power across the entire load range with low losses.

[0004] Therefore, people expect to improve the performance of synchronous converters. Summary of the Invention

[0005] This invention is defined by the claims.

[0006] According to an example of one aspect of the present invention, a synchronous converter device for driving a load is provided, the device comprising: a first switch connected between a first node and a switching node; a second switch connected between the switching node and a second node; a resonant circuit connected between the switching node and a third node configured to be connected to the load; and a control device configured to controllably activate and deactivate the first switch and the second switch in response to a control signal.

[0007] The control device is capable of operating in at least three modes.

[0008] There are at least three operating modes, including a first operating mode in which the control device responds to a control signal and uses pulse frequency control technology to controllably activate and deactivate the first switch and the second switch.

[0009] The at least three operating modes also include a second operating mode, wherein: the control device responds to the control signal to control the duration of activation of the first switch each time the first switch is activated; and the control device fixes the constant duration of activation of the second switch each time the second switch is activated.

[0010] The at least three operating modes also include a third operating mode, in which the control device uses switching frequency control technology to control the activation and deactivation frequencies of the first and second switches in response to a control signal.

[0011] The control device is configured to control which operating mode the control device operates in response to the desired power to be provided by the synchronous converter device.

[0012] The control device of the proposed synchronous converter apparatus is capable of controlling or changing the power supplied by the synchronous converter apparatus in response to a control signal. The operating mode of the control device depends on the desired power to be transmitted. This means that the control device can switch operating modes depending on the desired power, for example, switching to a more efficient, lower-loss, or lower-noise operating mode. This disclosure recognizes that different power transmission levels require different control techniques for utilizing the first and second switches to supply power.

[0013] This disclosure presents three different operating modes for controlling the switching of a synchronous converter device based on the power to be transmitted. Each mode responds to a control signal to control the power transmitted by the synchronous converter device.

[0014] The desired power supplied by the synchronous converter can be indicated by a control signal. This provides a reliable mechanism for controlling the power supplied by the synchronous converter while operating in the control mode most suitable for the power supplied by the synchronous converter.

[0015] In this way, the control device can be configured (in each operating mode) to effectively control the power provided by the synchronous converter device in response to the desired power to be transmitted.

[0016] The indication provided by the control signal can be, for example, an absolute indication (e.g., directly identifying the desired power level) or a relative / feedback indication (e.g., indicating the error between the current power level and the desired power level). Suitable methods for controlling the activation and deactivation of switches in response to these parameters will be apparent to those skilled in the art.

[0017] In some examples, the synchronous converter device includes a feedback device configured to generate a feedback signal in response to the power at the third node, wherein a control signal responds to this feedback signal. In this way, the activation and deactivation control of the switch responds to the power output by the synchronous converter device, thereby providing more precise and reliable control over the power output by the synchronous converter device.

[0018] The synchronous converter device may further include a comparison device configured to compare a feedback signal with a reference signal to generate a control signal. The reference signal can effectively represent the desired power level to be provided by the synchronous converter device. In this way, the control signal can indicate the error between the current power level and the desired power level.

[0019] In some examples, the feedback device includes a single resistor connected in series with the load driven by the synchronous converter; and the feedback signal can vary in response to the current through this single resistor. In this way, the synchronous converter can perform current feedback control on the power supplied to the load of the synchronous converter.

[0020] In some examples, the resonant circuit includes a transformer connected between the switching node and the third node.

[0021] The resonant circuit may include a capacitor device connected between the switching node and the second node.

[0022] The synchronous converter device may include a rectifier connected between the resonant circuit and the third node. The rectifier may include a single diode connected between the resonant circuit and the third node, or may be formed by a single diode connected between the resonant circuit and the third node.

[0023] The control device can be configured to operate in a first operating mode in response to a desired power drop below a first threshold. This method recognizes that pulse frequency control techniques are particularly advantageous, for example, more efficient than other techniques, when used to supply or provide relatively low levels of power.

[0024] The advantage of the first operating mode is that it avoids a (further) reduction in the energy transferred by the switching device in each switching cycle when the target power level is extremely low. It is well known that attempting to transfer very small levels of energy in each switching cycle is difficult to achieve precisely. By reducing the frequency of the energy pulses (using the first operating mode), precise control of the power transferred by the synchronous converter device can be achieved even at low power levels.

[0025] In some examples, the first threshold is no greater than 5% of the maximum power that the synchronous converter device can transmit.

[0026] The control device can be configured to operate in a second operating mode in response to the desired power falling between a first threshold and a higher second threshold.

[0027] If pulse frequency control is maintained for the increased power level, the switching frequencies of the first and second switches will increase similarly. As the power level continues to increase, this will adversely generate electromagnetic radiation at undesirable frequencies (e.g., frequencies greater than 150 kHz). The second-mode approach effectively reduces the switching frequency because the power level to be transmitted increases.

[0028] In some examples, the second threshold is not less than 60% of the maximum power that the synchronous converter device can transmit.

[0029] The control device can be configured to operate in a third operating mode in response to the desired power exceeding a second threshold.

[0030] The third operating mode recognizes that if the activation duration of the second switch is fixed, while the activation duration of the first switch is increased (i.e., as during the second operating mode), then eventually the two time periods will equalize. Further increasing the activation duration of the first switch will reduce the converter power. Therefore, an alternative operating mode can be used to further increase the power output by the synchronous converter.

[0031] In some examples, the resonant circuit is an LLC resonant circuit or an LLCC resonant circuit.

[0032] In some examples, the synchronous converter device includes a half-bridge inverter or a full-bridge inverter. The first switch and the second switch form part of the half-bridge inverter or the full-bridge inverter.

[0033] These and other aspects of the invention will be apparent from and illustrated in the embodiments described below. Attached Figure Description

[0034] To better understand the present invention and to more clearly demonstrate how to implement it, reference is now made to the accompanying drawings by way of example only, in which:

[0035] Figure 1 The figure illustrates a proposed synchronous converter device;

[0036] Figure 2 The waveform of the proposed control technique is illustrated.

[0037] Figure 3 The diagram illustrates the relationship between the operating mode and the expected power. Detailed Implementation

[0038] The present invention will now be described with reference to the accompanying drawings.

[0039] It should be understood that although the following detailed description and specific examples illustrate exemplary embodiments of the apparatus, system, and method, they are for illustrative purposes only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, system, and method of the present invention will be better understood from the following description, the appended claims, and the accompanying drawings. It should be understood that the drawings are schematic only and not drawn to scale. It should also be understood that all drawings use the same reference numerals to denote the same or similar parts.

[0040] This invention provides a mechanism for defining the operating modes of a control device for a synchronous converter device. The control device is configured to control the activation and deactivation of switches in the inverter of the synchronous converter device. The control device operates in at least one of three different operating modes in response to the power to be output or supplied by the synchronous converter.

[0041] The embodiments are based, at least in part, on the understanding that different possible operating modes of the control device are advantageous for using the inverter to provide different levels of power efficiently or effectively with the synchronous converter device.

[0042] Figure 1 The figure illustrates a proposed synchronous converter device 100 for driving a load LED.

[0043] The synchronous converter device 100 includes a first switch S1, a second switch S2, a resonant circuit 110, and a control device 150.

[0044] The first switch S1 is connected between the first node N1 and the switch node NX. The second switch S2 is connected between the switch node NX and the second node N2, which can be grounded or connected to a reference voltage. The resonant circuit 110 is connected between the switch node NX and the third node N3. The third node is configured to be connected to the load LED.

[0045] Both the first switch S1 and the second switch S2 can be implemented as corresponding field-effect transistors, such as MOSFETs or HEMTs (e.g., GaN HEMTs). However, any suitable form of electrically controllable switch can be used, such as any form of transistor with a body diode or diode activation mode.

[0046] The switch is active when it allows bidirectional current to flow; it is deactivated when it blocks or limits bidirectional current flow. Each switch may include or define a body diode that allows unidirectional current to flow in the deactivated state. The control device 150 may be configured, for example, to control the gate-source voltage at the switch to controllably activate and deactivate the switch.

[0047] Therefore, the control device can be configured to: control the voltage at the gate of a first switch (e.g., a first FET) to controllably activate and deactivate the first switch; and control the voltage at the gate of a second switch (e.g., a second FET) to controllably activate and deactivate the second switch.

[0048] Specifically, the control device 150 can define or output a first gate control signal S G1 It controls the voltage at the gate of the first switch; and the second gate control signal S. G2It controls the voltage at the gate of the second switch.

[0049] The alternative label for the first switch S1 is a high-side switch. The alternative label for the second switch S2 is a low-side switch. When the switches are implemented as FETs, the first switch S1 can be labeled as a first FET or a high-side FET, and the second switch S2 can be labeled as a second FET or a low-side FET.

[0050] To be used as an isolated load-resonant DC-DC converter, the power supply V IN The voltage at the first node N1 is supplied. The voltage at the third node N3 serves as the output of the converter. Therefore, when the converter 100 operates as a DC-DC converter, a load is connected to draw power from the third node N3. Different methods for controlling the activation of the first and second switches to perform the flyback DC-DC conversion process are widely accepted in the art. For example, an example method is disclosed by Medina-Garcia, Alfredo et al. in “Resonanthybrid flyback, a new topology for high density power adaptors.” Electronics 7.12 (2018): 363.

[0051] For example, power supply V IN It can be made by a rectifier bridge connected between the AC mains power supply and the synchronous converter device. Figure 1 (Not shown in the image) is generated. For example, power supply V... IN It can be supplied by batteries or cell packs. Clearly, the power source V... IN It is (typically) a DC power supply, but ripple voltage (e.g., not exceeding ±10% or ±5%) is considered acceptable.

[0052] It should be understood that the control device 150 is configured to controllably activate and deactivate the first switch S1 and the second switch S2. In the proposed method, this is in response to the control signal S. C And it was executed.

[0053] Specifically, the control signal can identify, indicate, or otherwise respond to changes in the desired power (hereinafter referred to as "desired power") supplied by the synchronous converter device to the load. For example, the control signal can indicate the desired power to be transmitted by the synchronous converter device. As another example, the control signal can determine to increase, decrease, or maintain the power transmitted by the synchronous converter device, for example, power that can be generated by a feedback loop as described later. In this way, the control signal can effectively indicate the desired power to be supplied by the synchronous converter device.

[0054] Therefore, the control signal can directly indicate the desired power to be transmitted by the synchronous converter device. Alternatively, the control signal can indicate changes in the desired power (e.g., it can be used to modify or change a buffer or stored value representing the desired power).

[0055] Control device 150 can process control signal Sc to determine how to control the first switch and the second switch. Specifically, control device 150 can generate gate control signal S. G1 and S G2 This is used to control the activation and deactivation of the first and second switches, as previously described.

[0056] Specifically, the control device 150, the first switch S1, and the second switch S2 can be considered as forming an inverter for a synchronous converter device, more specifically, a half-bridge inverter, since their function is to convert DC voltage to AC voltage. The control device 150 controls the activation and deactivation of the first and second switches, thereby effectively controlling the characteristics of the AC voltage received at the resonant slot.

[0057] The resonant circuit 110 may include or be formed of a resonant groove.

[0058] In the example shown, the resonant circuit 110 includes a first inductor Ls, a second inductor Lp, and a first capacitor device C. S They are connected in series with the first side of transformers W1 and W2. The first inductor Ls and the first capacitor C... S Both are connected in series between the switching node NX and the second node N2. The transformer windings w1 and w2 also act as inductors in the resonant circuit. As shown in the figure, the resonant circuit 110 may also include a second capacitor Cp connected in parallel with the transformers w1 and w2.

[0059] Transformers wl and w2 comprise a pair of windings wl and w2 formed by a first winding wl and a second winding w2. These windings wl and w2 are magnetically coupled to each other but electrically isolated. Elements electrically connected to the first winding wl (of the pair of windings) can be considered to be located on the first side or input side of the transformer. Elements electrically connected to the second winding w2 (of the pair of windings) can be considered to be located on the second side or output side of the transformer.

[0060] Transformers w1 and w2 can actually form or define the second inductor Lp in the resonant circuit. Therefore, in the actual implementation of the resonant circuit, the second inductor Lp can be omitted. More specifically, the mutual inductance of transformers w1 and w2 can perform the function of a second inductor.

[0061] The first winding w1 is connected in series with the first inductor Ls and in parallel with the second inductor Lp (if present) and the first capacitor device, between the switching node NX and the second node N2. The second winding w2 is electrically connected to the third node N3, here in parallel with the second capacitor device Cp.

[0062] In this way, the resonant circuit shown in the figure is formed as an LLC resonant circuit. An alternative resonant circuit is an LLC resonant circuit (which can be implemented by omitting the second capacitor Cp device).

[0063] In other embodiments, transformers w1 and w2 may be omitted, for example, and a second inductor Lp (together with the first inductor Ls and the first capacitor C) may be used. S (Series connection) can be used instead. If a second capacitor Cp exists, it can be connected in parallel with a second inductor Lp. Of course, this method provides a non-isolated synchronous converter device 100.

[0064] As shown in the figure, the synchronous converter device 100 may further include a rectifier 120 connected between the resonant circuit 110 and the third node N3. More specifically, in the example shown, the rectifier 120 is connected between the second winding w2 (of transformers w1 and w2) and the third node N3. If transformers w1 and w2 are omitted, the rectifier 120 may be connected between an intermediate node (located between the first inductor Ls and the second inductor Lp) and the third node N3.

[0065] In the illustrated example, the rectifier is a single diode connected between the resonant circuit and the third node.

[0066] The synchronous converter device 100 may also include a buffer capacitor C. B The buffer capacitor C B A connection is made between the third node N3 and ground or a reference voltage GND, which can be defined as the voltage at the fourth node N4. Preferably, the fourth node N4 is electrically isolated from the first side of the transformer, and more specifically, electrically isolated from the second node N2.

[0067] The voltage between the third node N3 and ground or reference voltage GND can define the voltage supplied to or provided to the load LED.

[0068] In the example shown, the load LED is implemented as an LED device (e.g., including one or more LEDs). In this way, a lighting device is also provided, which includes a synchronous converter device 100 and an LED device LED powered by the synchronous converter device 100.

[0069] However, the load LED can be replaced with any other load suitable for use by the synchronous converter device 100, such as a speaker, a sensing device, an antenna device, etc.

[0070] This disclosure proposes configuring control device 150 to operate in at least three operating modes (or simply "operating modes"). Control device 150 selects the operating mode in response to a desired power to be provided by the synchronous converter device, i.e., the (desired) power to be drawn from the load. As previously described, this can be indicated by a control signal Sc.

[0071] Different operating modes are designed to operate at different load levels, i.e., different power levels drawn by the load. This improves the efficiency of the synchronous converter device.

[0072] The desired power to be drawn by the load may change due to variations in load impedance (e.g., if an LED in the LED device forming the load fails); and / or variations in the desired current through the load (e.g., dimming control for an LED load).

[0073] Typically, the common characteristic of the operating modes is that the control device controls the first and second switches so that only one switch is active at a time. This is a characteristic of synchronous converter devices. Typically, the first and second switches are controlled to alternately activate and deactivate.

[0074] In some examples, a dead time is introduced between the deactivation of one switch and the activation of another switch. During the dead time, neither the first nor the second switch is activated. The dead time allows the voltage at the switching node to swing to the voltage at either the first or the second node, for example, to achieve zero-voltage switching. The dead time after the first switch deactivates can be referred to as the first dead time, and the dead time after the second switch deactivates can be referred to as the second dead time.

[0075] Figure 2 The first gate control signal S is illustrated graphically. G1 Second gate control signal S G2 The waveform illustrates the general control procedures or techniques performed by the control device (e.g., regardless of the operating mode). The waveform is presented as a change in voltage over time.

[0076] First gate control signal S G1 The waveform is represented by a solid line. Second gate control signal S G2 The waveform is represented by a dashed line.

[0077] First gate control signal S G1 Configured to activate alternately (e.g., when voltage V) H(when higher) and deactivation (e.g., when voltage V) L (At a lower level) First switch. Similarly, second gate control signal S G2 Configured to activate alternately (e.g., when voltage V) H (when higher) and deactivation (e.g., when voltage V) L (At lower levels) Second switch. The first and second gate control signals are synchronized to prevent the first and second switches from activating simultaneously.

[0078] The duration of the first switch activation (each time the first switch is activated) can be denoted as the first switch activation time t. ON1 The duration of the second switch activation (each time the second switch is activated) can be denoted as the second switch activation time t. ON2 The time interval between the deactivation of the first switch and the activation of the second switch (each time the first switch is deactivated) can be denoted as the first dead time t. d1 The duration between the deactivation of the second switch and the activation of the first switch (each time the second switch is deactivated) can be denoted as the second dead time t. d2 .

[0079] To simplify control, the first and second dead times can be the same. Alternatively, the first and second dead times can also be different from each other, for example, depending on the resonance condition of the resonant circuit, to achieve zero-voltage switching.

[0080] In other embodiments, the first and second dead time are omitted (i.e., the dead time is equal to 0).

[0081] In summary, and as Figure 2 As shown, it can be clearly seen that the control device can be configured to iteratively or cyclically execute a predetermined sequence of steps (in each operating mode). The predetermined sequence may include (executed in the following order): activating the first switch, waiting for the first switch to activate for a specified time, deactivating the first switch, waiting for a first dead time, activating the second switch, waiting for the second switch to activate for a specified time, deactivating the second switch, and waiting for a second dead time.

[0082] Figure 3 Three operating modes of the control device 150 are schematically shown. In each operating mode, the control device is configured to control the first switch activation time t in response to a control signal. ON1 The value (represented by solid line) and the second switch activation time t ON2 The value (represented by dashed lines).

[0083] For ease of illustration, in each operating mode, the control device is configured to control the first and / or second switch activation times in response to the desired power P to be provided by the synchronous converter device to the load (i.e., the “desired power” indicated by the control signal).

[0084] In the first operating mode 310, the control device responds to the control signal and uses pulse frequency control technology to controllably activate and deactivate the first switch and the second switch.

[0085] In pulse frequency control technology, the frequency response of the first switch in the active state is controlled by a control signal. As mentioned earlier, the control signal can identify or indicate changes in power to be transmitted by the synchronous converter device.

[0086] More specifically, most of the control over the power transmitted by the synchronous converter device is achieved by controlling the duration of the second switch activation each time the second switch is activated (i.e., the second switch activation time). Specifically, the second switch activation time can be reduced as the power transmitted by the synchronous converter device increases (i.e., causing the first switch to activate more frequently).

[0087] Therefore, during the first operating mode, the control device can be configured to shorten the second activation time in response to an increase in the desired power (the power to be drawn from the synchronous converter device). The control device can also be configured to prevent the shortening of the first activation time in response to an increase in the desired power (the power to be drawn from the synchronous converter device), for example, to maintain or increase the first activation time.

[0088] Preferably, during the first operating mode, the rate of change of the second switch activation time (in response to changes in the control signal) is greater than the rate of change of the first switch activation time. Specifically, during the first operating mode, the rate of change of the second switch activation time (in response to changes in the control signal) may be no less than 5 times the rate of change of the first switch activation time.

[0089] As an example, the activation time of the first switch can be fixed during the first operating mode. This ensures that the power transmitted by the synchronous converter device can be controlled by controlling the duration of activation of the second switch each time it is activated. Therefore, in some examples, when pulse frequency control techniques are implemented, the duration of activation of the first switch each time it is activated (i.e., the first switch activation time) is fixed.

[0090] During the first operating mode, the activation time of the second switch may be from the first maximum value t. ON2MAX (Related to the minimum switching frequency fs.min of the switch) Reduced to the first minimum value t ON2MIN (and the maximum switching frequency f of the switch) s.max (Related).

[0091] In the second operating mode 320, the control device responds to a control signal to control or modify the activation duration (i.e., the first switch activation time) each time the first switch is activated. Specifically, the control device may increase the first switch activation time to increase the desired power to be transmitted by the synchronous converter device.

[0092] In the second operating mode, the control device fixes the activation duration (i.e., the second switch activation time) each time the second switch is activated. In other words, during the second operating mode, the second switch activation time can be fixed or constant, for example, within a reasonable or measurable error range (e.g., ±5% or more preferably ±1%). In this case, for different values ​​of the first switch activation time and different activation / deactivation cycles of the second switch, the second switch activation time is fixed or constant (e.g., ±5% or more preferably ±1%). Preferably, the activation duration of the second switch each time it is activated is greater than zero.

[0093] In the third operating mode 330, the control device uses switching frequency control technology to control the activation and deactivation frequencies of the first and second switches in response to a control signal. In this method, the greater the power to be absorbed, the lower the activation and deactivation frequencies of the first and second switches.

[0094] During the third operating mode, the ratio of the first switch activation time to the second switch activation time can be the same. For example, the first switch activation time and the second switch activation time can be identical.

[0095] Various methods of switching frequency control technology have been widely used in this field.

[0096] Figure 3 The diagram also illustrates a method by which the control device determines which operating mode to use.

[0097] Specifically, the control device is configured to select an operating mode based on which of a plurality of ranges the desired power P falls into. More specifically, each operating mode is associated with a different range of desired power values.

[0098] Specifically, the control device can be configured to operate in a first operating mode in response to a desired power drop below a first threshold P1. Therefore, the control device can be configured to operate in the first operating mode in response to a desired power falling within a first range (e.g., from 0 to the first threshold).

[0099] Similarly, the control device can be configured to operate in a second operating mode in response to the desired power falling between a first threshold P1 and a second threshold P2. Therefore, the control device can be configured to operate in a second operating mode in response to the desired power falling within a second range (e.g., the range from the first threshold to the second threshold).

[0100] Similarly, in response to a desired power increase or exceeding a second threshold P2, the control device can be configured to operate in a third operating mode. Therefore, in response to a desired power decrease to a third range (e.g., from the second threshold P2 to the maximum power P that the synchronous converter device can transmit), the control device can be configured to operate in a third operating mode. MAX The control device can be configured to operate in a third operating mode.

[0101] (Multiple) thresholds can be determined by the maximum power P that the synchronous converter device can transmit. MAX Defined as a percentage.

[0102] Specifically, the first threshold P1 may be no greater than 5% of the maximum power that the synchronous converter device can transmit, for example, no greater than 2% of the maximum power, for example, no greater than 1% of the maximum power (e.g., 1% of the maximum power).

[0103] The second threshold P2 can be defined as not greater than (e.g., equal to) the desired power, at which the switching frequency of the first and second switches is not greater than the predetermined maximum frequency fs if the control device is operating in the first operating mode. MAX A predetermined maximum frequency can be defined as the frequency at which any stray electromagnetic radiation satisfies one or more predetermined frequency criteria. For example, a predetermined maximum frequency fs. MAX The power level may not exceed 150 kHz, for example, not exceeding 130 kHz. The precise power level may depend on the characteristics and / or component values ​​of the synchronous converter unit.

[0104] The second threshold P2 may be no less than 60% of the maximum power that the synchronous converter device can transmit, for example, no less than 70% of the maximum power, for example, no less than 75% of the maximum power (e.g., 75% of the maximum power).

[0105] The second threshold P2 can be defined as not greater than (for example, equal to) the desired power, at which the first switch activation time should be equal to the second switch activation time if the control device is operating in the second operating mode. This avoids the first switch activation time exceeding the second switch activation time.

[0106] Back Figure 1 The following describes the methods for generating control signals (for the control device) and using control signals (at the control device).

[0107] Specifically, the synchronous converter device may further include a feedback device 160, which is configured to respond to the power generation feedback signal V at the third node N3. FB The control signal responds to the feedback signal.

[0108] For example, a feedback device may include a single resistor R. S The resistor is configured to be connected in series with the load LED driven by the synchronous converter device. Feedback signal V FB It can change in response to the current flowing through a single resistor. Specifically, the single resistor R S The voltage across the terminals can be used as a feedback signal V. FB .

[0109] Feedback device 160 may include comparison device 161, which is configured to compare feedback signal V FB With reference signal V REF The comparison is performed to generate the control signal Sc.

[0110] Reference signal V REF This indicates the expected or desired power to be provided by the synchronous converter device, such as the expected current through the load. For example, when the load is formed by lamps such as LED devices, this expected current may change to alter or modify the dimming level of the load. In other examples, the expected or desired power is constant.

[0111] Specifically, the comparison device 161 may include an error amplifier 162 for generating an error signal S. e The error signal indicates the feedback signal V. FB With reference signal V REF The difference between them. This difference effectively represents the power error supplied to the load LED.

[0112] In the above method, the error signal S e This effectively indicates the error between the current flowing through the load and the reference current. However, those skilled in the art will readily understand how other forms of power monitoring or feedback can be utilized to gain advantages. For example, feedback device 160 can be configured such that the error signal indicates the difference between the voltage applied to the load (e.g., the voltage at the third node N3) and the reference voltage.

[0113] Comparison device 161 may further include amplifier 163, which is configured to amplify the error signal S e It also generates control signals.

[0114] In a specific example, amplifier 163 is a proportional-integral amplifier configured to amplify the error signal and its integral (e.g., using different gains), and then sum these two amplifications to generate a control signal. In this way, the control signal effectively represents the average error over a period of time.

[0115] More specifically, in the method using comparator 161, the control signal C generated from the comparator... SThis indicates the change in the desired power output by the synchronous converter device.

[0116] The control processor 150 may use this indication value to modify or adjust the value representing the desired power stored internally or in a buffer (e.g., increase or decrease the desired power). The operating mode of the control device may depend on this internally stored or buffered value representing the desired power, and therefore on the control signal. It is also understood that, in any operating mode, the control performed by the control device also depends on the control signal.

[0117] An alternative to using feedback device 160 is to use an open-loop control system, where the desired power is not defined with reference to the actual power output by the synchronous converter device. For example, the reference signal V REF It can be easily used as a control signal.

[0118] In some examples, where feedback device 160 is used, electrical isolation element 170 (such as an optocoupler) is configured to provide electrical isolation (i.e., electrical decoupling) between the feedback device and the first and second switches. For example, this electrical isolation element is positioned between feedback device 160 and control device 150, thereby electrically decoupling the control device from the feedback device.

[0119] In some examples, the synchronous converter device also includes a memory or storage device 180. This memory or storage device may store one or more predefined parameters, values, or characteristics for use by a control device. For example, the memory or storage device may store a minimum switching frequency, a maximum switching frequency, a minimum first switching activation time, a minimum second switching activation time, a first switching activation time for a first operating mode (i.e., during PFC), a first dead time, and / or a second dead time.

[0120] The control device 150 may be suitably configured to utilize one or more stored values. Those skilled in the art will understand how the functionality of the control device (e.g., in any operating mode) is constrained by these values.

[0121] In the example shown, the synchronous converter device contains only two switches, which function as a half-bridge inverter to power the resonant circuit. In other examples, the synchronous converter device includes four switches, which function as a full-bridge inverter to power the resonant circuit. In these methods, the four switches can be divided into two groups of switches, where switches in the same group are controlled in the same way as each other (i.e., simultaneously activated and deactivated). In this method, the first group of switches includes a first switch, and the second group of switches includes a second switch.

[0122] The embodiment comprises a control device. The control device can be implemented in various ways, using software and / or hardware, to perform a variety of desired functions. A processor is one example of a control device using one or more microprocessors, which can be programmed using software (e.g., microcode) to perform desired functions. However, the control device can be implemented with or without a processor, and can also be implemented as a combination of dedicated hardware performing some functions and processors (e.g., one or more programmed microprocessors and associated circuitry) performing other functions.

[0123] Examples of control device components that may be used in the various embodiments of this disclosure include, but are not limited to, conventional microprocessors, application-specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs).

[0124] In various implementations, the processor or control unit may be associated with one or more storage media, such as volatile and non-volatile computer memories like RAM, PROM, EPROM, and EEPROM. The storage media may be encoded with one or more programs that, when executed on one or more processors and / or control units, perform the desired function. The various storage media may be fixed within the processor or control unit or may be removable to allow one or more programs stored thereon to be loaded into the processor or control unit.

[0125] By studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement various modifications to the disclosed embodiments. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude multiple elements or steps.

[0126] The functions implemented by the control device can be achieved by a single processor or by multiple independent processing units, which together constitute the "processor". In some cases, these processing units may be geographically separated and communicate with each other via wired or wireless means.

[0127] The fact that certain measures are mentioned in different dependent claims does not mean that these measures cannot be combined and utilized.

[0128] Furthermore, a non-transitory storage medium is proposed for storing or carrying computer programs or computer code. When the program or code is executed together with a control device, the control device performs the functions described herein. The aforementioned computer program can be stored / distributed on suitable media, such as optical storage media or solid-state media, which can be provided together with or as part of other hardware; it can also be distributed in other forms, such as via the Internet or other wired or wireless communication systems.

[0129] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude multiple. If the term "suitable" is used in the claims or description, it should be noted that the word "suitable" is intended to be equivalent to "configured as". If the term "arrangement" is used in the claims or description, it should be noted that the word "arrangement" is intended to be equivalent to "system", and vice versa.

[0130] No reference numerals in the claims shall be construed as limiting the scope of the claims.

Claims

1. A synchronous converter device (100) for driving a load (LED), comprising: The first switch (SI) is connected between the first node (Nl) and the switch node (NX); The second switch (S2) is connected between the switch node and the second node (N2); A resonant circuit (110) is connected between the switching node and a third node (N3), the third node being configured to be connected to the load; and Control device (150) is configured to controllably activate and deactivate the first switch and the second switch in response to a control signal (Sc), wherein the control device is capable of operating in at least three operating modes, including: - First operating mode (310), in which the control device uses pulse frequency control technology to controllably activate and deactivate the first switch and the second switch in response to the control signal; - Second working mode (320), in the second working mode: - The control device responds to the control signal and controls the duration (t) for which the first switch is activated each time it is activated. ON1 );as well as - The control device fixes the second switch to remain activated for a constant duration (t) each time it is activated. ON2 );as well as - Third operating mode (330), in which the control device uses switching frequency control technology to control the activation and deactivation frequencies of the first switch and the second switch in response to the control signal. The control device is configured to control which operating mode it operates in response to the desired power to be provided by the synchronous converter device.

2. The synchronous converter device of claim 1, wherein the desired power to be provided by the synchronous converter device is indicated by the control signal.

3. The synchronous converter apparatus according to any one of claims 1 or 2, further comprising a feedback device (160) configured to generate a feedback signal (V) in response to the power at the third node. FB ), wherein the control signal is in response to the feedback signal.

4. The synchronous converter apparatus according to claim 3 further includes a comparison device (161) configured to compare the feedback signal with a reference signal to generate the control signal.

5. The synchronous converter device according to any one of claims 3 or 4, wherein: The feedback device includes a single resistor (R) S The single resistor (R) S The load driven by the synchronous converter device is connected in series; and The feedback signal changes in response to the current flowing through the single resistor.

6. The synchronous converter device according to any one of claims 1 to 5, wherein the resonant circuit includes a transformer (W1, W2) connected between the switching node and the third node.

7. The synchronous converter device according to any one of claims 1 to 6, wherein the resonant circuit includes a capacitor device (C) connected between the switching node and the second node. S ).

8. The synchronous converter device according to any one of claims 1 to 7, further comprising a rectifier (D1) connected between the resonant circuit and the third node.

9. The synchronous converter device according to claim 8, wherein the rectifier is a single diode connected between the resonant circuit and the third node.

10. The synchronous converter device according to any one of claims 1 to 9, wherein the control device is configured to operate in the first operating mode in response to the desired power dropping below a first threshold (P1).

11. The synchronous converter device according to claim 10, wherein the first threshold is not greater than the maximum power (P) that the synchronous converter device can transmit. MAX 5% of ).

12. The synchronous converter device according to any one of claims 10 or 11, wherein the control device is configured to operate in the second operating mode in response to the desired power being between the first threshold and a higher second threshold (P2).

13. The synchronous converter device according to claim 12, wherein the second threshold is not less than the maximum power (P) that the synchronous converter device can transmit. MAX 60% of ).

14. The synchronous converter apparatus according to any one of claims 12 or 13, wherein the control device is configured to operate in the third operating mode in response to the desired power rising above the second threshold.

15. The synchronous converter device according to any one of claims 1 to 14, wherein the resonant circuit is an LLC resonant circuit or an LLCC resonant circuit.

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