Energy conversion device and control method

Abstract

An energy conversion device (1) comprises: a resonator (30); a primary-side full bridge circuit (10) with a first switch (Q1), a second switch (Q2), a third switch (Q3) and a fourth switch (Q4); a secondary-side full bridge circuit (20) with a fifth switch (Q5), a sixth switch (Q6), a seventh switch (Q7) and an eighth switch (Q8); and a controller (40).The control unit (40) actuates the fifth switch (Q5), the sixth switch (Q6), the seventh switch (Q7) and the eighth switch (Q8) synchronously with control signals for the first switch (Q1), the second switch (Q2), the third switch (Q3) and the fourth switch (Q4) synchronously with control signals applied in a period that excludes a resonance period of the resonator (30) from a switching cycle of the first switch (Q1), the second switch (Q2), the third switch (Q3) and the fourth switch (Q4), and controls an on-time of the control signals with the length of the period as the upper limit.

Description

Technical field

[0001] The present disclosure relates to an energy conversion device capable of unidirectional or bidirectional energy conversion, and to a control method for the energy conversion device. State of the art

[0002] With the increasing importance of achieving a climate-neutral society, the demand is growing for charging circuits capable of efficiently charging home storage batteries and electric vehicle batteries. Such charging circuits require an isolated DC-DC converter, with resonant converters frequently used to achieve a compact size and higher efficiency. Among resonant converters, LLC converters in particular have attracted attention due to their ability to achieve high efficiency with simple circuitry.

[0003] LLC converters generally use frequency control to regulate output power. The loads supplied by LLC converters range from light to heavy loads, and to accommodate these loads, the frequency control range becomes wide, requiring measures to meet all operating conditions (e.g., electromagnetic compatibility (EMC) measures).

[0004] In response to this problem, patent literature (PTL) 1 describes an LLC-type DC-DC converter that regulates the output power by using duty cycle control to give the transformer current an asymmetric waveform between positive and negative. Citation list for patent literature

[0005] PTL 1 Japanese unpublished patent application no. 2022-17179 Summary of the invention; Technical task

[0006] However, since the transformer current in the DC-DC converter disclosed in PTL 1 has an asymmetric waveform between positive and negative, this has negative effects such as a deterioration of the common-mode noise.

[0007] In view of this, the present disclosure provides an energy conversion device and the like which can effectively control the output power while limiting the width of the frequency control range. Solution to the problem

[0008] An energy conversion device according to the present disclosure is capable of unidirectional or bidirectional power conversion and comprises: a resonator including a transformer and a resonant capacitor; a primary-side full-bridge circuit connected to a primary side of the resonator; a secondary-side full-bridge circuit connected to a secondary side of the resonator; and a control device controlling the primary-side full-bridge circuit and the secondary-side full-bridge circuit. The primary-side full-bridge circuit comprises a first switching element arranged on a high side of a first strand, a second switching element arranged on a low side of the first strand, a third switching element arranged on a high side of a second strand, and a fourth switching element arranged on a low side of the second strand.The secondary-side full bridge circuit comprises a fifth switching element located on a high side of a third strand, a sixth switching element located on a low side of the third strand, a seventh switching element located on a high side of a fourth strand, and an eighth switching element located on a low side of the fourth strand.The control system calculates a time interval that excludes a resonator resonance interval from a switching cycle of the first switching element, the second switching element, the third switching element, and the fourth switching element; operates the fifth switching element, the sixth switching element, the seventh switching element, and the eighth switching element synchronously with control signals for the first switching element, the second switching element, the third switching element, and the fourth switching element by means of control signals applied within the time interval; and controls an on-time of the control signals with a length of the time interval as an upper limit.

[0009] A control method according to the present disclosure is provided for an energy conversion device that enables unidirectional or bidirectional power conversion. The energy conversion device comprises: a resonator with a transformer and a resonant capacitor; a primary-side full-bridge circuit connected to a primary side of the resonator; and a secondary-side full-bridge circuit connected to a secondary side of the resonator. The primary-side full-bridge circuit comprises a first switching element arranged on a high side of a first strand, a second switching element arranged on a low side of the first strand, a third switching element arranged on a high side of a second strand, and a fourth switching element arranged on a low side of the second strand.The secondary-side full bridge circuit comprises a fifth switching element located on a high side of a third strand, a sixth switching element located on a low side of the third strand, a seventh switching element located on a high side of a fourth strand, and an eighth switching element located on a low side of the fourth strand.The control method comprises: calculating a time interval that excludes a resonator resonance interval from a switching cycle of the first switching element, the second switching element, the third switching element, and the fourth switching element; operating the fifth switching element, the sixth switching element, the seventh switching element, and the eighth switching element synchronously with control signals for the first switching element, the second switching element, the third switching element, and the fourth switching element by means of control signals applied in the time interval; and controlling a switch-on time of the control signals with a length of the time interval as an upper limit.

[0010] General or specific aspects of the present disclosure may be realized as a system, method, integrated circuit, computer program or computer-readable recording medium such as CD-ROM or any combination thereof. Advantageous effects of the invention

[0011] The energy conversion device and the like according to one aspect of the present disclosure are able to effectively control the output power while limiting the width of the frequency control range. Brief description of the characters Fig. 1 Fig. Figure 1 is a circuit diagram illustrating an example of an energy conversion device according to an embodiment of the present disclosure. Fig. 2 Fig. Figure 2 is a diagram illustrating the operation of a control system according to an embodiment of the present disclosure. Fig. 3 Fig. Figure 3 is a diagram illustrating an example of the operation of a controller in a first mode according to an embodiment of the present disclosure. Fig. 4 Fig. Figure 4 is a diagram illustrating the effects of the functions of a controller in a first mode according to an embodiment of the present disclosure. Fig. 5 Fig. Figure 5 is a diagram illustrating an example of the operation of a controller in a second mode according to an embodiment of the present disclosure. Fig. 6 Fig. Figure 6 is a diagram illustrating an example of the operation of a controller in a phase-shift control mode according to an embodiment of the present disclosure. Fig. 7 Fig. Figure 7 is a diagram illustrating an example of the operation of a controller in an intermittent operating mode according to an embodiment of the present disclosure. Fig. 8 Fig. Figure 8 is a flowchart illustrating an example of a control method according to a further embodiment of the present disclosure. Description of embodiments

[0012] In the following, embodiments of the present disclosure are described in detail with reference to the figures.

[0013] The embodiments described below each illustrate a general or specific example. The numerical values, shapes, materials, elements, arrangement and connection of the elements, steps, sequence of steps, etc., shown in the following embodiments are merely examples and therefore do not limit the scope of this disclosure. embodiment

[0014] The following describes an energy conversion device according to one embodiment.

[0015] Fig. Figure 1 is a circuit diagram illustrating an example of an energy conversion device 1 according to the embodiment.

[0016] Energy conversion device 1 is an energy conversion device capable of performing unidirectional or bidirectional energy conversion. For example, it is an isolated DC-DC converter that increases or decreases an input voltage to a predetermined voltage and outputs the voltage. For instance, energy conversion device 1 is an LLC converter. An LLC converter is a circuit that utilizes LLC resonance through the leakage inductance of a transformer, the magnetizing inductance, and a resonant capacitor. In an LLC converter, changing the switching frequency alters the ratio between the input and output voltage (gain), thereby producing the desired power output. However, the following describes energy conversion device 1 that can control the output power without frequency control.

[0017] The energy conversion device 1 comprises terminals t1, t2, t3, and t4. Terminal t1 is an input terminal. Terminal t2 is a ground terminal. Terminal t3 is an output terminal. Terminal t4 is a ground terminal. Since the energy conversion device 1 is an isolated DC-DC converter, terminals t2 and t4 are electrically isolated from each other.

[0018] The energy conversion device 1 comprises a primary-side full bridge circuit 10, a secondary-side full bridge circuit 20, a resonator 30, capacitors Cein and Caus, and a controller 40. Note that the capacitors Cein and Caus need not be elements of the energy conversion device 1.

[0019] The capacitor Cein is an input capacitor connected between terminal t1 and terminal t2, and the capacitor Caus is an output capacitor (smoothing capacitor) connected between terminal t3 and terminal t4.

[0020] The primary-side full-bridge circuit 10 is connected to the primary side of the resonator 30. The primary-side full-bridge circuit 10 comprises a first switching element arranged on a high side of a first strand, a second switching element arranged on a low side of the first strand, a third switching element arranged on a high side of a second strand, and a fourth switching element arranged on a low side of the second strand.

[0021] The primary-side full bridge circuit 10 comprises switches Q1, Q2, Q3, and Q4. Switch Q1 is an example of the first switching element, switch Q2 is an example of the second switching element, switch Q3 is an example of the third switching element, and switch Q4 is an example of the fourth switching element.

[0022] For example, switch Q1 is an N-channel metal-oxide-semiconductor field-effect transistor (MOSFET). The sink of switch Q1 is connected to terminal t1, and the source of switch Q1 is connected to the sink of switch Q2.

[0023] For example, switch Q2 is an N-channel MOSFET. The sink of switch Q2 is connected to the source of switch Q1, and the source of switch Q2 is connected to terminal t2.

[0024] For example, switch Q3 is an N-channel MOSFET. The sink of switch Q3 is connected to terminal t1, and the source of switch Q3 is connected to the sink of switch Q4.

[0025] For example, switch Q4 is an N-channel MOSFET. The sink of switch Q4 is connected to the source of switch Q3, and the source of switch Q4 is connected to terminal t2.

[0026] The secondary-side full-bridge circuit 20 is connected to the secondary side of the resonator 30. The secondary-side full-bridge circuit 20 comprises a fifth switching element located on the high side of a third strand, a sixth switching element located on the low side of the third strand, a seventh switching element located on the high side of a fourth strand, and an eighth switching element located on the low side of the fourth strand. The secondary-side full-bridge circuit 20 also functions as a rectifier circuit capable of full-wave rectification.

[0027] The secondary-side full bridge circuit 20 comprises switches Q5, Q6, Q7 and Q8. Switch Q5 is an example of the fifth switching element, switch Q6 is an example of the sixth switching element, switch Q7 is an example of the seventh switching element and switch Q8 is an example of the eighth switching element.

[0028] For example, switch Q5 is an N-channel MOSFET. The sink of switch Q5 is connected to terminal t3, and the source of switch Q5 is connected to the sink of switch Q6.

[0029] For example, switch Q6 is an N-channel MOSFET. The sink of switch Q6 is connected to the source of switch Q5, and the source of switch Q6 is connected to terminal t4.

[0030] For example, switch Q7 is an N-channel MOSFET. The sink of switch Q7 is connected to terminal t3, and the source of switch Q7 is connected to the sink of switch Q8.

[0031] For example, switch Q8 is an N-channel MOSFET. The sink of switch Q8 is connected to the source of switch Q7, and the source of switch Q8 is connected to terminal t4.

[0032] The resonator 30 includes the transformer T and the capacitor Cr.

[0033] Capacitor Cr is an example of a resonant capacitor. Capacitor Cr is connected to a node between switch Q1 and switch Q2 in the first branch.

[0034] Transformer T is an insulated transformer comprising a primary winding and a secondary winding that are electrically isolated from each other. One end of the primary winding of transformer T is connected via capacitor Cr to a junction between switches Q1 and Q2 in the first phase, and the other end of the primary winding of transformer T is connected to a junction between switches Q3 and Q4 in the second phase. One end of the secondary winding of transformer T is connected to a junction between switches Q5 and Q6 in the third phase, and the other end of the secondary winding of transformer T is connected to a junction between switches Q7 and Q8 in the fourth phase.

[0035] It should be noted that the capacitor Cr can be connected to a junction between switches Q3 and Q4 in the second phase. In such cases, one end of the primary winding of transformer T is connected to a junction between switches Q1 and Q2 in the first phase, and the other end of the primary winding of transformer T is connected via the capacitor Cr to a junction between switches Q3 and Q4 in the second phase.

[0036] The controller 40 controls the primary-side full-bridge circuit 10 and the secondary-side full-bridge circuit 20. More precisely, the controller 40 is a circuit for controlling the switching (turning on and off) of switches (e.g., switches Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8) contained in the energy conversion device 1. For example, the controller 40 controls the switching of switches Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 by controlling a gate control circuit (not shown in the figures) that is connected to the gates of switches Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 via a PWM generator (not shown in the figures) or the like.

[0037] The control unit 40, for example, is a computer with a processor (microprocessor) and memory. The memory can be, for example, read-only memory (ROM) and random-access memory (RAM) and can store programs executed by the processor. The control unit 40 is, for example, a microcontroller.

[0038] The controller 40 calculates a time interval that excludes the resonance period of the resonator 30 (a resonance period due to the capacitance of the capacitor Cr and the leakage inductance of the transformer T) from the switching cycle of switches Q1, Q2, Q3, and Q4. It then actuates switches Q5, Q6, Q7, and Q8 synchronously with the control signals for switches Q1, Q2, Q3, and Q4 by means of control signals applied within this time interval. The controller 40 also controls the on-time of the control signals, with the length of the time interval described above as the upper limit.

[0039] Here, the functionality of control unit 40 is described with reference to Fig. 2 described in more detail.

[0040] Fig. Figure 2 is a diagram to illustrate the operation of the control unit 40 according to the embodiment.

[0041] For example, in Fig. As shown in Figure 2, controller 40 controls the switching of switches Q1 and Q4 in the same phase and also controls the switching of switches Q2 and Q3 in the same phase. It should be noted that controller 40 controls switches Q1, Q2, Q3, and Q4 such that the phase difference between the switching of switches Q1 and Q4 and the switching of switches Q2 and Q3 is 180 degrees. Accordingly, the control signals for switches Q1, Q2, Q3, and Q4 are, for example, as shown in Figure 2. Fig. Figure 2 illustrates this. More precisely, switches Q1 and Q4 repeatedly switch on and off with a duty cycle of 50%, switches Q2 and Q3 repeatedly switch on and off with a duty cycle of 50%, switches Q2 and Q3 are in an off state when switches Q1 and Q4 are in an on state, and switches Q1 and Q4 are in an off state when switches Q2 and Q3 are in an on state.

[0042] When, via control unit 40, switches Q1 and Q4 are switched on and switches Q2 and Q3 are switched off, or when switches Q2 and Q3 are switched on and switches Q1 and Q4 are switched off, current (primary current) flows through the primary winding of transformer T. The primary current oscillates with a resonant period of resonator 30. When current flows through the primary winding of transformer T, current (secondary current) also flows through the secondary winding of transformer T. The secondary current likewise oscillates with a resonant period of resonator 30. Accordingly, the primary and secondary currents are as described in Fig. 2 shown.

[0043] The controller 40 calculates a time interval that corresponds to a resonance time interval of the resonator 30 (for example, the one in Fig. 2 shown resonance half-cycle) from a switching cycle of switches Q1, Q2, Q3 and Q4 (for example, the one shown in Fig. The switching half-cycle shown in Figure 2, which is a period during which the switches are in an on state at a duty cycle of 50%, is excluded. During this period, no current flows to the load connected to terminals t3 and t4. This period is also referred to as the non-energy-settling period.

[0044] The controller 40 actuates switches Q5, Q6, Q7, and Q8 synchronously with the control signals for switches Q1, Q2, Q3, and Q4 by means of control signals applied during the non-energy-setting period. Here, the controller 40 performs, as in Fig. Figure 2 shows a pulse width control for the on-times of switches Q5, Q6, Q7, and Q8. It should be noted that, as shown in Fig. Figure 2 shows that the control signals for switches Q1, Q2, Q3, and Q4 and the drive signals for switches Q5, Q6, Q7, and Q8 are synchronized. Note that synchronizing a control signal and a drive signal means that there is a fixed relationship between the activation time of the control signal and the activation time of the drive signal. In this description, activation of the drive signal after a fixed time interval following activation of the control signal is described as synchronization of the control signal and the drive signal.

[0045] The controller 40 has a first mode and a second mode as control modes for switching switches Q1, Q2, Q3, Q4, Q5, Q6, Q7 and Q8. First, the first mode will be described.

[0046] Fig. Figure 3 is a diagram illustrating an example of the operation of the controller 40 in the first mode according to the embodiment. Fig. Figure 3 shows, from top to bottom, timing diagrams of the gate signals of switches Q1, Q4, Q5, and Q8; the gate signals of switches Q2, Q3, Q6, and Q7; the voltage generated in the secondary winding of transformer T (transformer secondary voltage); the current flowing through the primary winding of transformer T (transformer primary current); the excitation current of transformer T (transformer excitation current); the voltage fed into the primary winding of transformer T (transformer input voltage); and the excitation voltage of transformer T (transformer excitation voltage). The same applies to Fig. 5, which will be described later.

[0047] As in Fig. As shown in Figure 3, in the first mode, the controller 40 uses the control signals to turn on switches Q5 and Q8 before turning off switches Q1 and Q4 from an on state. In the first mode, the controller 40 uses the control signals to turn on switches Q6 and Q7 before turning off switches Q2 and Q3 from an on state. The non-energy-setting period is the time before switches Q1 and Q4 are turned off from an on state (a period that exists in the second half of the time during which switches Q1 and Q4 are on), and the time before switches Q2 and Q3 are turned off from an on state (a period that exists in the second half of the on-time of switches Q2 and Q3).

[0048] It should be noted that the upper limit of the duration of a period before switches Q1 and Q4 are switched off from the on state, and the duration of a period before switches Q2 and Q3 are switched off from the on state, corresponds to the non-energy-setting period. In other words, the end of the period before switches Q1 and Q4 are switched off from the on state is the time at which switches Q1 and Q4 are switched off, and the start of the period occurs at a time that precedes the time at which switches Q1 and Q4 are switched off by a duration that does not exceed the length of the non-energy-setting period.The end of the period before switches Q2 and Q3 are switched off from the on state is the time at which switches Q2 and Q3 are switched off, and the start of the period occurs at a time that precedes the time at which switches Q2 and Q3 are switched off by a duration that does not exceed the length of the off-state period. Therefore, the controller 40 controls the switch-on time of the control signals with the length of the off-state period as the upper limit.

[0049] The energy conversion device 1, which is an LLC converter, is a circuit capable of achieving a gain of 1 or more (i.e., an increase in output power) by setting the switching frequency to a frequency lower than the resonant frequency of resonator 30 (the resonant frequency due to the capacitance of capacitor Cr and the leakage inductance of transformer T). Here, setting the switching frequency to a frequency lower than the resonant frequency of resonator 30 corresponds to a resonant current phase that precedes the phase of the input voltage (transformer input voltage) of resonator 30. In other words, by having the resonant current phase precede the phase of the transformer input voltage, the output power can be increased.In the first mode, the controller 40 controls the switching of switches Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 such that the phase of the resonant current leads the phase of the input voltage of the resonant circuit, while the switching frequency is fixed. The operations of the controller 40 in the first mode are described in more detail below.

[0050] As in area A of Fig. As shown in Figure 3, the controller 40 switches on switches Q6 and Q7 during a non-power-setting period, i.e., a period of time before switches Q2 and Q3 are switched off from an on state.

[0051] Accordingly, as in area B of Fig. Figure 3 shows the polarity of the transformer's secondary voltage reversed. As this shows, the polarity reversal occurs earlier than with the conventional transformer secondary voltage, represented by the dashed line (specifically, the transformer's secondary voltage when switches Q6 and Q7 are not controlled during the non-power-setting period).

[0052] As in section C of Fig. As shown in Figure 3, when the polarity of the secondary voltage of the transformer is reversed, the polarity of the excitation voltage of the transformer is also reversed in response to the reversal of the polarity of the secondary voltage of the transformer.

[0053] As in area D of Fig. As shown in Figure 3, the transformer excitation current reaches an extreme value earlier than in the conventional case because the polarity of the transformer excitation voltage is reversed earlier. More precisely, since the polarity reversal phase leads the transformer excitation voltage, the transformer excitation current also leads. Because the resonant current is superimposed on the transformer excitation current, its phase also leads when the transformer excitation current leads. Since the resonant current phase leads the transformer input voltage, the output power can be increased. It should be noted that by further extending the on-time of switches Q6 and Q7 during the non-energy-settling period, the resonant current phase leads even further, and the output power can be increased even more.

[0054] Fig. Figure 4 is a diagram illustrating the effects of operating the controller 40 in the first mode according to the embodiment. In the diagram shown in Fig. In diagram 4 (output current vs. duty cycle), the horizontal axis represents the duty cycle of switches Q5, Q6, Q7, and Q8 during the non-energy-setting period, and the vertical axis represents the output current. The output current is directly related to the output power, with the output power increasing proportionally to the output current.

[0055] As in Fig. As shown in Figure 4, the output current, and therefore the output power, increases when the on-time of switches Q5, Q6, Q7, and Q8 during the off-time period is extended. More precisely, this shows that the energy conversion device 1 has a power adjustment function that can handle loads from approximately 1 A (low load) to approximately 15 A (high load). For example, if the output voltage is 250 V, the output power can be adjusted from 250 W to 3.7 kW.

[0056] Thus, in the first mode, the output power can be increased while maintaining a fixed switching frequency.

[0057] Next, the second mode of control 40 will be described.

[0058] Fig. Figure 5 is a diagram illustrating an example of the operation of the controller 40 in the second mode according to the embodiment.

[0059] As in Fig. As shown in Figure 5, in the second mode, the controller 40 uses the control signals to switch on switches Q6 and Q7 before switching off switches Q1 and Q4 from an on state. In the second mode, the controller 40 uses the control signals to switch on switches Q5 and Q8 before switching off switches Q2 and Q3 from an on state.

[0060] The energy conversion device 1, which is an LLC converter, is a circuit capable of achieving a gain of less than 1 (i.e., a reduction in output power) by setting the switching frequency to a frequency higher than the resonant frequency of resonator 30. Here, setting the switching frequency to a frequency higher than the resonant frequency of resonator 30 corresponds to a phase shift of the resonant current behind the phase of the input voltage (transformer input voltage) of resonator 30. In other words, by keeping the phase of the resonant current behind the phase of the transformer input voltage, the output power can be reduced. In the second mode, the controller 40 controls the switching of switches Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 such that the phase of the resonant current lags behind the phase of the input voltage of the resonant circuit, while the switching frequency remains fixed.Here, the processes of control unit 40 in the second mode are described in more detail.

[0061] As in area A of Fig. As shown in Figure 5, the controller 40 switches on switches Q6 and Q7 during a non-power-setting period, i.e., a period of time before switches Q1 and Q4 are switched off from an on state.

[0062] Accordingly, as in area B of Fig. Figure 5 shows the polarity of the transformer's secondary voltage reversed. As this shows, the polarity reversal occurs later than with the conventional transformer secondary voltage, indicated by the dashed line (specifically, the transformer's secondary voltage when switches Q6 and Q7 are not controlled during the non-power-setting period).

[0063] As in section C of Fig. As shown in Figure 5, when the polarity of the secondary voltage of the transformer is reversed, the polarity of the excitation voltage of the transformer is also reversed in response to the reversal of the polarity of the secondary voltage of the transformer.

[0064] As in area D of Fig. As shown in Figure 5, the transformer excitation current reaches an extreme value at a later time than in the conventional case because the polarity of the transformer excitation voltage is reversed at a later time. More precisely, since the phase of the polarity reversal lags behind the transformer excitation voltage, the phase of the transformer excitation current also lags behind. Because the resonant current is superimposed on the transformer excitation current, its phase also lags behind when the phase of the transformer excitation current lags behind. Since the phase of the resonant current lags behind the phase of the transformer input voltage, the output power can be reduced. It should be noted that by further extending the on-time of switches Q6 and Q7 during the non-energy-settling period, the phase of the resonant current lags even further, and the output power can be reduced even further.

[0065] Although the representation of a diagram to explain the operation of the control 40 in the second mode according to the embodiment is omitted, the output current and thus the output power decreases when the on-time of the switches Q5, Q6, Q7 and Q8 during the non-energy-setting period increases.

[0066] Thus, in the second mode, the output power can be reduced while maintaining a fixed switching frequency.

[0067] It should be noted that when the controller 40 operates in the second mode, a simple delay of the polarity reversal phase in the transformer excitation voltage may not be sufficient to reduce the output power of the energy conversion device 1 to the target level. Therefore, the controller 40 may further have at least one phase-shift control mode, which controls the phase between the switching of switches Q1 and Q2 and the switching of switches Q3 and Q4, and an intermittent operating mode, which intermittently controls the switching of switches Q1, Q2, Q3, and Q4. The phase-shift control mode will be described first.

[0068] Fig. Figure 6 is a diagram illustrating an example of the operation of the controller 40 in phase-shift control mode according to the embodiment. Fig. Figure 6 shows, from top to bottom, timing diagrams of the gate signals of switches Q1 and Q4, the gate signals of switches Q2 and Q3, the voltage generated in the secondary winding of transformer T (transformer secondary voltage), the current flowing through the primary winding of transformer T (transformer primary current), the excitation current of transformer T (transformer excitation current), the voltage fed into the primary winding of transformer T (transformer input voltage), and the excitation voltage of transformer T (transformer excitation voltage).

[0069] As in Fig. As shown in Figure 6, in phase-shift control mode, the controller 40 controls the switching of switches Q1, Q2, Q3, and Q4 such that the switching phase of switches Q3 and Q4 is delayed relative to the switching phase of switches Q1 and Q2. It should be noted that in phase-shift control mode, the controller 40 does not input any signals to the gates of switches Q5, Q6, Q7, and Q8; switches Q5, Q6, Q7, and Q8 are in an off state; and the secondary-side full-bridge circuit 20 functions as a full-wave rectifier circuit using the body diodes of switches Q5, Q6, Q7, and Q8.

[0070] Accordingly, the waveform of the transformer input voltage (in other words, the output voltage of the primary-side full-bridge circuit 10) is not a square wave, but a waveform that includes a period in which the voltage is 0 V due to the phase shift caused by the on-state of switch Q1 and the off-state of switch Q4, as well as a period in which the voltage is 0 V due to the phase shift caused by the on-state of switch Q2 and the off-state of switch Q3. Since the period during which the transformer excitation voltage is applied is thus shortened, the gain (output power) can be reduced.

[0071] Next, the intermittent operating mode will be described.

[0072] Fig. Figure 7 is a diagram illustrating an example of the operation of the controller 40 in intermittent operating mode according to the embodiment. Fig. Figure 7 shows, from top to bottom, timing diagrams of the gate signals of switches Q1 and Q4, the gate signals of switches Q2 and Q3, and the output current of energy conversion device 1.

[0073] As in Fig. As shown in Figure 7, the controller 40 intermittently controls the switching of switches Q1, Q2, Q3, and Q4 in intermittent operating mode. More precisely, the controller 40 repeatedly switches switches Q1, Q2, Q3, and Q4 on and off in a first time interval, switches them to an off state in a subsequent second time interval, and then repeats the control cycles. Accordingly, the output current waveform is intermittent, being present in the first time interval and absent in the second. In intermittent operating mode, the average current (average power) can decrease over the long term.

[0074] As described above, a period that excludes the resonant period of resonator 30 from the switching cycle of switches Q1, Q2, Q3, and Q4 is a non-energy-settling period during which no current flows to the load. During the non-energy-settling period, the point in time at which the polarity of the voltage generated in the secondary winding of transformer T (transformer secondary voltage) is reversed can be set by switching on switches Q5, Q6, Q7, and Q8 for a specific duration. When the polarity of the transformer secondary voltage is reversed, the polarity of the transformer T's excitation voltage is also reversed in response to the reversal of the transformer's secondary voltage polarity. In other words, the point in time at which the polarity of the transformer T's excitation voltage is reversed (in other words, the phase of the polarity reversal of the transformer T's excitation voltage) can be set.

[0075] For example, if the polarity reversal phase of the transformer T's excitation voltage is advanced, the phase of the transformer T's excitation current is present. Since the resonant current is superimposed on the excitation current, the phase of the resonant current is also present when the phase of the excitation current is present, and the output power of the energy conversion device 1 can be increased. Conversely, if the polarity reversal phase of the transformer T's excitation voltage is delayed, the phase of the transformer T's excitation current lags behind. Since the resonant current is superimposed on the excitation current, the phase of the resonant current also lags behind when the phase of the excitation current lags behind, and the output power of the energy conversion device 1 can be decreased.By controlling the turn-on time of the drive signals for switches Q5, Q6, Q7, and Q8 during the non-energy-setting period, the output power can be regulated without frequency control. This effectively regulates the output power while simultaneously limiting the width of the frequency control range. It should be noted that in the DC-DC converter described in PTL 1, the transformer current exhibits an asymmetrical waveform between positive and negative, which has negative effects such as a deterioration of the common-mode noise. In contrast, in the energy conversion device 1, the transformer current exhibits a symmetrical waveform between positive and negative, making a deterioration of the noise performance unlikely.

[0076] By limiting the frequency control range, miniaturization of the transformer T, increased efficiency, miniaturization of the EMC filter, and similar improvements can be achieved. Since the energy conversion device 1 does not need to operate at a low switching frequency, miniaturization of the transformer T is possible. Furthermore, since the energy conversion device 1 does not need to operate at a high switching frequency, AC resistance losses are reduced and efficiency can be improved. Because the frequency control range is narrow or a fixed value, EMC countermeasures can be implemented with a narrowband EMC filter, and miniaturization of the EMC filter is possible.

[0077] It should be noted that the energy conversion device 1 is capable of bidirectional power conversion and that terminal t3 can serve as the input terminal, while terminal t1 can serve as the output terminal. In such cases, the control described above for switches Q1, Q2, Q3, and Q4 is applied to switches Q5, Q6, Q7, and Q8, and vice versa. In these cases, capacitor Caus serves as the input capacitor and capacitor Cein as the output capacitor. (Other embodiments)

[0078] Above, one or more embodiments have been described as one or more examples of the techniques according to the present disclosure. However, the techniques according to the present disclosure are not limited to these examples; various modifications, substitutions, additions, omissions, etc., can be applied to the embodiments. For example, the following variations are also included in one embodiment of the present disclosure.

[0079] For example, the embodiment described above includes an example where the energy conversion device is an LLC converter. However, the disclosure is not limited thereto, and the energy conversion device may be a resonant converter comprising a resonator with series and / or parallel LC circuits, such as an LCC converter or a CLLC converter.

[0080] In the embodiment described above, for example, the LLC converter includes the magnetizing inductance and leakage inductance of the transformer, as well as a resonant capacitor. However, instead of the leakage inductance, a separate inductor corresponding to the leakage inductance can also be provided.

[0081] For example, the controller 40 can also have a frequency control mode that controls the switching frequency and adjusts the output power by controlling the switching frequency.

[0082] The present disclosure can be realized, for example, not only as an energy conversion device, but also as a control method for controlling the energy conversion device (in particular as a control method comprising steps (processes) that are carried out by elements (in particular the control 40) that are contained in the energy conversion device).

[0083] Fig. Figure 8 is a flowchart illustrating an example of a control procedure according to a further embodiment.

[0084] For example, the control method for an energy conversion device is arranged, enabling unidirectional or bidirectional power conversion. The energy conversion device comprises: a resonator with a transformer and a resonant capacitor; a primary-side full-bridge circuit connected to a primary side of the resonator; and a secondary-side full-bridge circuit connected to a secondary side of the resonator. The primary-side full-bridge circuit comprises a first switching element located on a high side of a first strand, a second switching element located on a low side of the first strand, a third switching element located on a high side of a second strand, and a fourth switching element located on a low side of the second strand.The secondary-side full-bridge circuit comprises a fifth switching element located on a high side of a third strand, a sixth switching element located on a low side of the third strand, a seventh switching element located on a high side of a fourth strand, and an eighth switching element located on a low side of the fourth strand. The control method comprises: as in . Fig.Figure 8 shows the calculation of a time interval that excludes a resonator resonance interval from a switching cycle of the first switching element, the second switching element, the third switching element and the fourth switching element (step S11); operating the fifth switching element, the sixth switching element, the seventh switching element and the eighth switching element synchronously with control signals for the first switching element, the second switching element, the third switching element and the fourth switching element by means of control signals applied in the time interval (step S12); and controlling a switch-on time of the control signals with a length of the time interval as the upper limit (step S13).

[0085] For example, the present disclosure can be implemented as a program that causes a computer (processor) to execute the steps contained in the control method. Furthermore, the present disclosure can be implemented as a non-transitory, computer-readable recording medium, such as a CD-ROM, on which the program is recorded.

[0086] If, for example, the present disclosure is implemented as a program (software), each step is performed while the program is running using hardware resources such as a computer's CPU, memory, and input / output circuits. In other words, each step is performed while the CPU retrieves data from memory or the input / output circuits, performs calculations, and outputs the results of the calculations to memory or the input / output circuits.

[0087] In the embodiment described above, each element contained in the energy conversion device can be configured using dedicated hardware or implemented by executing a software program suitable for that element. Each element can be implemented by a program execution unit such as a CPU or processor, which reads and executes a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0088] Some or all of the functions of the energy conversion device according to the above embodiment are typically implemented as LSI circuits, i.e., integrated circuits. These elements can be integrated onto individual chips, or some or all of the elements can be integrated onto a single chip. Circuit integration is not limited to LSI; the elements can be implemented using dedicated circuitry or a general-purpose processor. A field-programmable gate array (FPGA) can be used, allowing programming after the LSI circuits have been fabricated, or a reconfigurable processor can be used, allowing reconfiguration of the connections and settings of the circuit cells within the LSI circuits.

[0089] If, due to advances in semiconductor technology or other derived technologies, a new technology for circuit integration emerges that replaces LSI, the circuit integration of each element contained in the energy conversion device can, of course, be carried out using this technology.

[0090] Embodiments that are obtained by a person skilled in the art through various modifications to one of the embodiments, or embodiments that are realized by any combination of elements and functions in the embodiments that do not deviate from the essence of the present disclosure, are also included in the present disclosure. (Additional notes)

[0091] Based on the foregoing description of the embodiments, the following technologies are disclosed.

[0092] (Technology 1) An energy conversion device enabling unidirectional or bidirectional power conversion, including: a resonator with a transformer and a resonant capacitor; a primary-side full-bridge circuit connected to a primary side of the resonator; a secondary-side full-bridge circuit connected to a secondary side of the resonator; and a controller controlling the primary-side full-bridge circuit and the secondary-side full-bridge circuit. The primary-side full-bridge circuit comprises a first switching element located on a high side of a first string, a second switching element located on a low side of the first string, a third switching element located on a high side of a second string, and a fourth switching element located on a low side of the second string.The secondary-side full bridge circuit comprises a fifth switching element located on a high side of a third strand, a sixth switching element located on a low side of the third strand, a seventh switching element located on a high side of a fourth strand, and an eighth switching element located on a low side of the fourth strand.The control system: calculates a time interval that excludes a resonator resonance interval from a switching cycle of the first switching element, the second switching element, the third switching element, and the fourth switching element; operates the fifth switching element, the sixth switching element, the seventh switching element, and the eighth switching element synchronously with control signals for the first switching element, the second switching element, the third switching element, and the fourth switching element by means of control signals applied within the time interval; and controls an on-time of the control signals with a length of the time interval as the upper limit.

[0093] Thus, a period that excludes a resonator resonance interval from the switching cycle of the first, second, third, and fourth elements is a non-energy-settling period, during which no current flows to the load. During the non-energy-settling period, the moment at which the polarity of the voltage generated in the transformer's secondary winding (transformer secondary voltage) is reversed can be set by switching on the fifth, sixth, seventh, and eighth switching elements for a specific duration. When the polarity of the transformer secondary voltage is reversed, the polarity of the transformer excitation voltage is also reversed in response to the reversal of the transformer secondary voltage polarity.In other words, the point in time at which the polarity of the transformer's excitation voltage is reversed (in other words, the phase of the polarity reversal of the transformer's excitation voltage) can be set.

[0094] For example, if the polarity reversal phase of the transformer's excitation voltage is advanced, the phase of the transformer's excitation current leads. Since the resonant current is superimposed on the excitation current, its phase also leads when the excitation current leads, and the output power of the energy conversion device can be increased. Conversely, if the polarity reversal phase of the transformer's excitation voltage is delayed, the phase of the transformer's excitation current lags. Since the resonant current is superimposed on the excitation current, its phase also lags when the excitation current lags, and the output power of the energy conversion device can be decreased.By controlling the on-time of the drive signals for the fifth switching element, the sixth switching element, the seventh switching element and the eighth switching element during the non-energy-setting period, the output power can therefore be controlled without frequency control, thus effectively controlling the output power while limiting the width of the frequency control range.

[0095] (Technology 2) The energy conversion device according to Technology 1, wherein the control: switches on the fifth switching element and the eighth switching element by the control signals before the first switching element and the fourth switching element are switched off from a switched-on state; and switches on the sixth switching element and the seventh switching element by the control signals before the second switching element and the third switching element are switched off from a switched-on state.

[0096] This allows the polarity reversal phase of the transformer's excitation voltage to be brought forward and the output power of the energy conversion device to be increased.

[0097] (Technology 3) The energy conversion device according to Technology 1, wherein the control: switches on the sixth switching element and the seventh switching element by the control signals before the first switching element and the fourth switching element are switched off from a switched-on state; and switches on the fifth switching element and the eighth switching element by the control signals before the second switching element and the third switching element are switched off from a switched-on state.

[0098] This allows the polarity reversal phase of the transformer's excitation voltage to be delayed and the output power of the energy conversion device to be reduced.

[0099] (Technology 4) Energy conversion device according to one of techniques 1 to 3, wherein the control further controls a phase between the switching of the first switching element and the second switching element and the switching of the third switching element and the fourth switching element.

[0100] This allows the output power of the energy conversion device to be reduced. For example, if a simple delay in the phase of the polarity reversal of the transformer's excitation voltage is insufficient to reduce the output power of the energy conversion device to the target power, the output power of the energy conversion device can be reduced to the target power by controlling the phase.

[0101] (Technology 5) Energy conversion device according to one of techniques 1 to 4, wherein the control further intermittently controls the switching of the first switching element, the second switching element, the third switching element and the fourth switching element.

[0102] This allows the output power of the energy conversion device to be reduced. For example, if a simple delay in the polarity reversal phase of the transformer's excitation voltage is insufficient to reduce the output power of the energy conversion device to the target power, the output power of the energy conversion device can be reduced to the target power by intermittently controlling the switching process.

[0103] (Technology 6) A control method for an energy conversion device that enables unidirectional or bidirectional power conversion. The energy conversion device comprises: a resonator with a transformer and a resonant capacitor; a primary-side full-bridge circuit connected to a primary side of the resonator; and a secondary-side full-bridge circuit connected to a secondary side of the resonator. The primary-side full-bridge circuit comprises a first switching element located on a high side of a first branch, a second switching element located on a low side of the first branch, a third switching element located on a high side of a second branch, and a fourth switching element located on a low side of the second branch.The secondary-side full bridge circuit comprises a fifth switching element located on a high side of a third strand, a sixth switching element located on a low side of the third strand, a seventh switching element located on a high side of a fourth strand, and an eighth switching element located on a low side of the fourth strand.The control method comprises: calculating a time interval that excludes a resonator resonance interval from a switching cycle of the first switching element, the second switching element, the third switching element, and the fourth switching element; operating the fifth switching element, the sixth switching element, the seventh switching element, and the eighth switching element synchronously with control signals for the first switching element, the second switching element, the third switching element, and the fourth switching element by means of control signals applied in the time interval; and controlling a switch-on time of the control signals with a length of the time interval as an upper limit.

[0104] This allows a control method to be provided that is capable of effectively controlling the output power while limiting the width of the frequency control range. Industrial applicability

[0105] The present disclosure is applicable to isolated DC-DC converters and the like. List of reference symbols 1 Energy conversion device 10 Primary-side full bridge circuit 2 0 Secondary-side full bridge circuit 30 Resonator 40 Control Cein, Caus, Cr capacitor Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 switches T transformer t1, t2, t3, t4 connection QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-17179

[0005]

Claims

[1] An energy conversion device capable of unidirectional or bidirectional energy conversion, the energy conversion device comprising: a resonator comprising a transformer and a resonant capacitor; a primary-side full bridge circuit connected to a primary side of the resonator; a secondary-side full bridge circuit connected to a secondary side of the resonator; and a controller that controls the primary-side full bridge circuit and the secondary-side full bridge circuit, wherein The primary-side full bridge circuit comprises a first switching element located on a high side of a first strand, a second switching element located on a low side of the first strand, a third switching element located on a high side of a second strand, and a fourth switching element located on a low side of the second strand. The secondary-side full-bridge circuit comprises a fifth switching element located on a high side of a third strand, a sixth switching element located on a low side of the third strand, a seventh switching element located on a high side of a fourth strand, and an eighth switching element located on a low side of the fourth strand, wherein the control: a time span is calculated that excludes a resonance time span of the resonator from a switching cycle of the first switching element, the second switching element, the third switching element and the fourth switching element; the fifth switching element, the sixth switching element, the seventh switching element and the eighth switching element synchronously with control signals for the first switching element, the second switching element, translation of the originally filed PCT claims, the third switching element and the fourth switching element by control signals applied in the time span; and The on-time of the control signals is controlled by an upper limit set by the length of the time span. [2] The energy conversion device according to claim 1, wherein the control the fifth and eighth switching elements are switched on by the control signals before the first and fourth switching elements are switched off from an on state; and The sixth and seventh switching elements are switched on by the control signals before the second and third switching elements are switched off from an on state. [3] The energy conversion device according to claim 1, wherein the control: the sixth and seventh switching elements are switched on by the control signals before the first and fourth switching elements are switched off from an on state; and The fifth and eighth switching elements are switched on by the control signals before the second and third switching elements are switched off from an on state. [4] The energy conversion device according to one of claims 1 to 3, wherein the control further controls a phase between the switching of the first switching element and the second switching element and the switching of the third switching element and the fourth switching element, translation of the originally filed PCT claims. [5] The energy conversion device according to one of claims 1 to 3, wherein the control further intermittently controls the switching of the first switching element, the second switching element, the third switching element and the fourth switching element. [6] Control method for an energy conversion device capable of unidirectional or bidirectional power conversion, wherein the energy conversion device comprises: a resonator with a transformer and a resonant capacitor; a primary-side full bridge circuit connected to a primary side of the resonator; and a secondary-side full bridge circuit connected to a secondary side of the resonator, wherein the primary-side full-bridge circuit comprises a first switching element located on a high side of a first strand, a second switching element located on a low side of the first strand, a third switching element located on a high side of a second strand, and a fourth switching element located on a low side of the second strand, and wherein the secondary-side full-bridge circuit comprises a fifth switching element located on a high side of a third strand, a sixth switching element located on a low side of the third strand, a seventh switching element located on a high side of a fourth strand, and an eighth switching element located on a low side of the fourth strand, The control procedure includes: Translation of the originally filed PCT claims Calculating a time interval that excludes a resonance time interval of the resonator from a switching cycle of the first switching element, the second switching element, the third switching element and the fourth switching element; Operating the fifth, sixth, seventh, and eighth switching elements synchronously with control signals for the first, second, third, and fourth switching elements by means of control signals applied during the time interval; and Controlling the activation time of the control signals with a time span as the upper limit.

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