Power conversion device

Abstract

The present disclosure relates to a power conversion device. A power conversion device according to an embodiment of the present disclosure comprises: a transformer; a first switching element and a second switching element disposed on an input side of the transformer and connected in series with each other; an inductor connected to one end of the input side of the transformer; a third switching element and a fourth switching element respectively connected to the other end of the input side of the transformer; and a clamp capacitor connected between the fourth switching element and the third switching element, wherein, while the second switching element and the fourth switching element are turned on, the turn-off timing of the fourth switching element is delayed relative to that of the second switching element. Accordingly, switching loss can be reduced.

Description

power conversion device

[0001] The present disclosure relates to a power conversion device, and more particularly, to a power conversion device capable of reducing switching loss.

[0002] Electric vehicles that run on electricity, or hybrid vehicles that combine internal combustion engines and these, generate their output using motors and batteries.

[0003] Meanwhile, to drive the motor, an inverter is required to convert DC voltage into AC voltage, and the inverter uses the DC voltage of the battery and converts it into AC voltage.

[0004] Meanwhile, power conversion devices used for power conversion have problems with loss in switching elements.

[0005] Prior art, Korean Publication No. 10-2021-0156578, relates to an adaptive phase-shift delay control method and device for a two-switch forward converter, and discloses an adaptive phase-shift delay controller that reduces loss during a switching process and thus increases the efficiency of the system.

[0006] However, according to prior literature, there is a disadvantage in that loss occurs when either the first switching element or the second switching element is turned on. Furthermore, since hard switching is performed while the input voltages of both the first switching element and the second switching element are clamped, there is a disadvantage in that significant loss occurs due to the parasitic capacitor of the switching element.

[0007] The technical problem of the present disclosure is to provide a power conversion device capable of reducing switching loss.

[0008] The technical problem of the present disclosure is to provide a power conversion device capable of reducing switching loss by distributing it to multiple switching elements.

[0009] A power conversion device according to an embodiment of the present disclosure for solving the above technical problem comprises a transformer, a first switching element and a second switching element which are arranged on an input side of the transformer and are connected in series with each other, an inductor connected to one end of the input side of the transformer, a third switching element and a fourth switching element which are each connected to the other end of the input side of the transformer, and a clamp capacitor connected between the fourth switching element and the third switching element, and when the second switching element and the fourth switching element are turned on, the turn-off time of the fourth switching element is delayed compared to the turn-off time of the second switching element.

[0010] Meanwhile, the power conversion device according to the embodiment of the present disclosure may further include an input voltage detection unit that detects an input voltage input to the first switching element, and a control unit that controls the first to fourth switching elements based on the detected input voltage.

[0011] Meanwhile, the control unit can control the delay period of the delay to increase as the level of the input voltage increases.

[0012] Meanwhile, the control unit can vary the turn-on duty of the second switching element or the turn-on duty of the fourth switching element based on the level of the input voltage.

[0013] Meanwhile, the control unit can control the turn-on duty of the second switching element or the turn-on duty of the fourth switching element to increase as the level of the input voltage decreases.

[0014] Meanwhile, the control unit can turn on the first switching element after the delay-off of the fourth switching element.

[0015] Meanwhile, the control unit can turn on the first switching element after the delay-off of the fourth switching element, and can turn on the third switching element after the turn-on of the first switching element.

[0016] Meanwhile, the control unit may turn on the first switching element after the delay-off of the fourth switching element when the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is less than a reference value, and may cause the first switching element to perform a valley switching operation when the delay-off of the fourth switching element is performed.

[0017] Meanwhile, the control unit may turn on the first switching element after the delay-off of the fourth switching element when the turn-on duty of the first switching element or the turn-on duty of the third switching element is greater than or equal to a reference value, turn on the first switching element after the turn-on of the fourth switching element, and turn on the third switching element after the turn-on of the first switching element, and when the third switching element is turned on, the third switching element may perform a valley switching operation.

[0018] Meanwhile, the control unit turns on the first switching element after the delay-off of the fourth switching element when the level of the input voltage is greater than the level of the voltage of the clamp capacitor, and the first switching element can perform a valley switching operation when the delay-off of the fourth switching element is performed.

[0019] Meanwhile, the control unit, when the level of the input voltage is lower than or equal to the level of the voltage of the clamp capacitor, turns on the first switching element after the delay-off of the fourth switching element, turns on the third switching element after the turn-on of the first switching element, and when the third switching element is turned on, the third switching element can perform a valley switching operation.

[0020] Meanwhile, at the end of the delay, the voltage across the third switching element may be equal to the voltage across the clamp capacitor.

[0021] Meanwhile, the inductance of the inductor may be greater than the inductance of the leakage inductor on the input side of the transformer.

[0022] A power conversion device according to an embodiment of the present disclosure may further include a first diode connected to one end of the output side of the transformer, and a second diode connected to one end of the output side of the transformer.

[0023] Meanwhile, during the first period, based on the turn-on of the first switching element and the third switching element, current can flow through the first diode, and after the first period, based on the turn-on of the second switching element and the fourth switching element, current can flow through the second diode.

[0024] Meanwhile, when the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is less than the reference value, the turn-off time of the fourth switching element is delayed from the turn-off time of the second switching element, and based on the turn-off of the second switching element and the turn-on of the fourth switching element, current may flow only through the second diode, and then current may flow through the first diode and the second diode, respectively.

[0025] Meanwhile, based on the turn-on of the first switching element, current can flow through the first diode and the second diode, respectively.

[0026] Meanwhile, when the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is greater than the reference value, the turn-off time of the fourth switching element is delayed from the turn-off time of the second switching element, and current can flow in the second diode based on the turn-off of the second switching element and the turn-on of the fourth switching element.

[0027] Meanwhile, based on the turn-on of the first switching element, current may flow only through the second diode, and then current may flow through the first diode and the second diode, respectively.

[0028] Meanwhile, a power conversion device according to another embodiment of the present disclosure comprises a transformer, a first switching element and a second switching element which are arranged on an input side of the transformer and are connected in series with each other, an inductor connected to one end of the input side of the transformer, a third switching element and a fourth switching element which are respectively connected to the other end of the input side of the transformer, a clamp capacitor connected between the fourth switching element and the third switching element, and a control unit which controls the first to fourth switching elements, wherein the control unit delays the turn-off time of the fourth switching element more than the turn-off time of the second switching element when the second switching element and the fourth switching element are turned on, and when the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is less than a reference value, turns on the first switching element after the delay-off of the fourth switching element, and when the delay-off of the fourth switching element occurs, the first switching element performs a valley switching operation.

[0029] Meanwhile, a power conversion device according to another embodiment of the present disclosure comprises a transformer, a first switching element and a second switching element which are arranged on an input side of the transformer and are connected in series with each other, an inductor connected to one end of the input side of the transformer, a third switching element and a fourth switching element which are respectively connected to the other end of the input side of the transformer, a clamp capacitor connected between the fourth switching element and the third switching element, and a control unit which controls the first to fourth switching elements, wherein the control unit delays the turn-off time of the fourth switching element more than the turn-off time of the second switching element when the second switching element and the fourth switching element are turned on, and when the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is equal to or greater than a reference value, turns on the first switching element after the delay-off of the fourth switching element, and when the first switching element is turned on, the first switching element performs a valley switching operation, and after the turn-on of the first switching element, the third switching element Turn on.

[0030] A power conversion device according to an embodiment of the present disclosure comprises a transformer, a first switching element and a second switching element which are arranged on an input side of the transformer and are connected in series with each other, an inductor connected to one end of the input side of the transformer, a third switching element and a fourth switching element which are each connected to the other end of the input side of the transformer, and a clamp capacitor connected between the fourth switching element and the third switching element, wherein when the second switching element and the fourth switching element are turned on, the turn-off time of the fourth switching element is delayed compared to the turn-off time of the second switching element. Accordingly, switching loss can be reduced. In particular, switching loss can be reduced by distributing it to a plurality of switching elements.

[0031] Meanwhile, the power conversion device according to an embodiment of the present disclosure may further include an input voltage detection unit that detects an input voltage input to the first switching element, and a control unit that controls the first to fourth switching elements based on the detected input voltage. Accordingly, switching loss can be reduced.

[0032] Meanwhile, the control unit can control the delay period to increase as the input voltage level increases. Accordingly, switching loss can be reduced.

[0033] Meanwhile, the control unit can vary the turn-on duty of the second switching element or the turn-on duty of the fourth switching element based on the level of the input voltage. Accordingly, switching loss can be reduced.

[0034] Meanwhile, the control unit can control the turn-on duty of the second switching element or the turn-on duty of the fourth switching element to increase as the level of the input voltage decreases. Accordingly, switching loss can be reduced.

[0035] Meanwhile, the control unit can turn on the first switching element after the delay-off of the fourth switching element. Accordingly, switching loss can be reduced.

[0036] Meanwhile, the control unit can turn on the first switching element after the delay-off of the fourth switching element, and turn on the third switching element after the turn-on of the first switching element. Accordingly, switching loss can be reduced.

[0037] Meanwhile, the control unit turns on the first switching element after the fourth switching element is delayed off when the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is less than a reference value, and the first switching element can perform a valley switching operation when the fourth switching element is delayed off. Accordingly, switching loss can be reduced.

[0038] Meanwhile, if the turn-on duty of the first switching element or the turn-on duty of the third switching element is greater than or equal to a reference value, the control unit turns on the first switching element after the delay-off of the fourth switching element, turns on the third switching element after the turn-on of the first switching element, and when the third switching element is turned on, the third switching element can perform a valley switching operation. Accordingly, switching loss can be reduced.

[0039] Meanwhile, the control unit turns on the first switching element after the delay-off of the fourth switching element when the level of the input voltage is greater than the voltage level of the clamp capacitor, and the first switching element can perform a valley switching operation when the delay-off of the fourth switching element is performed. Accordingly, switching loss can be reduced.

[0040] Meanwhile, the control unit, when the level of the input voltage is lower than or equal to the voltage level of the clamp capacitor, turns on the first switching element after the delay-off of the fourth switching element, turns on the third switching element after the turn-on of the first switching element, and when the third switching element is turned on, the third switching element can perform a valley switching operation. Accordingly, switching loss can be reduced.

[0041] Meanwhile, at the end of the delay, the voltage across the third switching element can be equal to the voltage across the clamp capacitor. This reduces switching loss.

[0042] Meanwhile, the inductance of the inductor can be greater than the inductance of the leakage inductor on the input side of the transformer. This reduces switching losses.

[0043] A power conversion device according to an embodiment of the present disclosure may further include a first diode connected to one end of the output side of the transformer and a second diode connected to one end of the output side of the transformer. Accordingly, switching loss can be reduced.

[0044] Meanwhile, during the first period, based on the turn-on of the first switching element and the third switching element, current flows through the first diode, and after the first period, based on the turn-on of the second switching element and the fourth switching element, current can flow through the second diode. Accordingly, switching loss can be reduced.

[0045] Meanwhile, when the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is less than the reference value, the turn-off timing of the fourth switching element is delayed from the turn-off timing of the second switching element, and based on the turn-off of the second switching element and the turn-on of the fourth switching element, current may flow only through the second diode, and then through the first diode and the second diode, respectively. Accordingly, switching loss can be reduced.

[0046] Meanwhile, based on the turn-on of the first switching element, current can flow through the first diode and the second diode, respectively. Accordingly, switching loss can be reduced.

[0047] Meanwhile, if the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is greater than the reference value, the turn-off timing of the fourth switching element is delayed compared to the turn-off timing of the second switching element, and current can flow to the second diode based on the turn-off of the second switching element and the turn-on of the fourth switching element. Accordingly, switching loss can be reduced.

[0048] Meanwhile, based on the turn-on of the first switching element, current can flow only through the second diode, and then through the first and second diodes respectively. Accordingly, switching loss can be reduced.

[0049] Meanwhile, a power conversion device according to another embodiment of the present disclosure comprises a transformer, a first switching element and a second switching element which are arranged on an input side of the transformer and are connected in series with each other, an inductor connected to one end of the input side of the transformer, a third switching element and a fourth switching element which are respectively connected to the other end of the input side of the transformer, a clamp capacitor connected between the fourth switching element and the third switching element, and a control unit which controls the first to fourth switching elements, wherein the control unit delays the turn-off time of the fourth switching element compared to the turn-off time of the second switching element when the second switching element and the fourth switching element are turned on, and when the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is less than a reference value, the first switching element is turned on after the delay-off of the fourth switching element, and when the delay-off of the fourth switching element is performed, the first switching element performs a valley switching operation. Accordingly, switching loss can be reduced.

[0050] Meanwhile, a power conversion device according to another embodiment of the present disclosure comprises a transformer, a first switching element and a second switching element which are arranged on an input side of the transformer and are connected in series with each other, an inductor connected to one end of the input side of the transformer, a third switching element and a fourth switching element which are respectively connected to the other end of the input side of the transformer, a clamp capacitor connected between the fourth switching element and the third switching element, and a control unit which controls the first to fourth switching elements, wherein the control unit delays the turn-off time of the fourth switching element more than the turn-off time of the second switching element when the second switching element and the fourth switching element are turned on, and when the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is equal to or greater than a reference value, turns on the first switching element after the delay-off of the fourth switching element, and when the first switching element is turned on, the first switching element performs a valley switching operation, and after the turn-on of the first switching element, the third switching element Turn on. Accordingly, switching loss can be reduced.

[0051] FIG. 1 is a schematic drawing showing a body of a vehicle according to one embodiment of the present disclosure.

[0052] FIG. 2 is an example of a motor drive system according to one embodiment of the present disclosure.

[0053] Figure 3 illustrates an example of an internal block diagram of the motor driving device of Figure 2.

[0054] Fig. 4 is an example of an internal circuit diagram of the motor driving device of Fig. 3.

[0055] Fig. 5 is an example of an internal block diagram of the inverter control unit of Fig. 4.

[0056] FIG. 6 is a diagram illustrating the operation of a battery and an inverter related to the present disclosure.

[0057] FIG. 7 is a block diagram illustrating a power conversion device according to an embodiment of the present disclosure.

[0058] Fig. 8 is a drawing illustrating an example of the operation of the power conversion device of Fig. 7.

[0059] FIG. 9 is a drawing illustrating an example of a dc / dc converter in the power conversion device of FIG. 7.

[0060] Figures 10a to 17c are drawings referenced in the operation description of Figure 9.

[0061] Hereinafter, the present disclosure will be described in more detail with reference to the drawings.

[0062] The suffixes "module" and "part" used in the following description are given solely for the convenience of writing this specification and do not impart any particularly significant meaning or role to the components themselves. Therefore, the terms "module" and "part" may be used interchangeably.

[0063] FIG. 1 is a schematic drawing showing a body of a vehicle according to one embodiment of the present disclosure.

[0064] Referring to the drawings, a vehicle (100) according to an embodiment of the present disclosure may include a battery (205) that supplies voltage, a motor driving device (200) that receives voltage from the battery (205), a motor (250) that is driven and rotates by the motor driving device (200), front wheels (150) and rear wheels (155) that are rotated by the motor (250), a front suspension device (160) and a rear suspension device (165) that block vibrations of the road surface from being transmitted to the vehicle body, and an inclination detection unit (190) that detects an inclination angle of the vehicle body. Meanwhile, a driving gear (not shown) that converts the rotational speed of the motor (250) based on a gear ratio may be additionally provided.

[0065] The battery (205) supplies voltage to the motor drive device (200). In particular, it supplies direct current voltage to the capacitor (C) in the motor drive device (200).

[0066] Such a battery (205) may be formed by a set of multiple unit cells. The multiple unit cells may be managed by a battery management system (BMS) to maintain a constant voltage, and may discharge a constant voltage by the battery management system.

[0067] For example, the battery management system can detect the voltage (Vbat) of the battery (205) and transmit it to an electronic control unit (not shown) or an inverter control unit (250) within the motor drive device (200), and when the battery voltage (Vbat) falls below a lower limit, the battery can supply a DC voltage stored in a capacitor (C) within the motor drive device (200). In addition, when the battery voltage (Vbat) rises above an upper limit, the battery management system can also supply a DC voltage to the capacitor (C) within the motor drive device (200).

[0068] The battery (205) is preferably composed of a secondary battery that can be charged and discharged, but is not limited thereto.

[0069] The motor drive device (200) receives a direct current voltage from the battery (205) through a voltage input cable (120). The motor drive device (200) converts the direct current voltage received from the battery (205) into an alternating current voltage and supplies it to the motor (250). The converted alternating current voltage is preferably a three-phase alternating current voltage. The motor drive device (200) supplies a three-phase alternating current voltage to the motor (250) through a three-phase output cable (125) provided in the motor drive device (200).

[0070] The motor drive device (200) of Fig. 1 illustrates a three-phase output cable (125) composed of three cables, but three cables may be provided within a single cable.

[0071] Meanwhile, the motor driving device (200) according to the embodiment of the present disclosure is described below in FIG. 3.

[0072] The motor (250) includes a stator (131) that is fixed and does not rotate, and a rotor (135) that rotates. The motor (250) is provided with an input cable (140) and receives an AC voltage supplied from a motor driving device (200). The motor (250) may be, for example, a three-phase motor, and when a voltage-variable / frequency-variable AC voltage of each phase is applied to the coils of each phase's stator, the rotational speed of the rotor varies based on the applied frequency.

[0073] The motor (250) can take various forms, such as an induction motor, a BLDC motor (blushless DC motor), and a reluctance motor.

[0074] Meanwhile, a drive gear (not shown) may be provided on one side of the motor (250). The drive gear converts the rotational energy of the motor (250) based on a gear ratio. The rotational energy output from the drive gear is transmitted to the front wheels (150) and / or the rear wheels (155) to move the vehicle (100).

[0075] The front suspension (160) and rear suspension (165) support the front wheels (150) and rear wheels (155) respectively with respect to the vehicle body. The vertical directions of the front suspension (160) and rear suspension (165) are supported by springs or damping mechanisms to prevent road vibrations from reaching the vehicle body.

[0076] The front wheels (150) may further be equipped with a steering device (not shown). The steering device is a device that controls the direction of the front wheels (150) to drive the vehicle (100) in the direction intended by the driver.

[0077] Meanwhile, although not shown in the drawing, the vehicle (100) may further include an electronic controller for controlling electronic devices throughout the vehicle. The electronic controller (not shown) controls each device so that it can operate, display, etc. In addition, it may also control the battery management system described above.

[0078] In addition, the control unit (170 in FIG. 2) can generate driving command values ​​according to various driving modes (driving mode, reverse mode, neutral mode, parking mode, etc.) based on detection signals from an inclination detection unit (not shown) that detects an inclination angle of the vehicle (100), a speed detection unit (not shown) that detects a speed of the vehicle (100), a brake detection unit (not shown) according to the operation of the brake pedal, an accelerator detection unit (not shown) according to the operation of the accelerator pedal, etc. The driving command value at this time can be, for example, a torque command value or a torque command value.

[0079] Meanwhile, the vehicle (100) according to the embodiment of the present disclosure may be a concept that includes a pure electric vehicle using a battery and a motor, as well as a hybrid electric vehicle using a battery and a motor while using an engine.

[0080] At this time, the hybrid electric vehicle may further be equipped with a switching means capable of selecting at least one of a battery and an engine, and a transmission.

[0081] Meanwhile, hybrid electric vehicles can be divided into a series method that converts mechanical energy output from the engine into electrical energy to drive the motor, a parallel method that simultaneously uses mechanical energy output from the engine and electrical energy from the battery, and a series-parallel method that combines the two.

[0082] FIG. 2 is an example of a motor drive system according to one embodiment of the present disclosure.

[0083] Referring to the drawings, a motor driving system according to one embodiment of the present disclosure may include a vehicle (100) and a server (500).

[0084] Here, the server (500) may be a server operated by the manufacturer of the motor drive device (200) or the vehicle (100), or may correspond to a mobile terminal of the driver of the motor drive device (200) or the vehicle (100).

[0085] Meanwhile, the vehicle (100) may be equipped with an input unit (120), a communication unit (130), a memory (140), a control unit (170), and a motor driving device (200).

[0086] The input unit (120) is equipped with operation buttons, keys, etc., and can output input signals for turning the voltage on / off, setting the operation, etc. of the vehicle (100).

[0087] The communication unit (130) can exchange data with peripheral devices, such as a server (500), wired or wirelessly, or wirelessly with a remote server, etc. For example, it can perform mobile communication such as 4G or 5G, infrared (IR) communication, RF communication, Bluetooth communication, Zigbee communication, WiFi communication, etc.

[0088] Meanwhile, the memory (140) of the vehicle (100) can store data necessary for the operation of the vehicle (100). For example, data regarding the operating time and operating mode of the motor driving device (200) can be stored.

[0089] Additionally, the memory (140) of the vehicle (100) can store management data including power consumption information of the vehicle, recommended driving information, current driving information, and management information.

[0090] Additionally, the memory (140) of the vehicle (100) can store diagnostic data including vehicle operation information, driving information, and error information.

[0091] The control unit (170) can control each unit within the vehicle (100). For example, the control unit (170) can control the input unit (120), the communication unit (130), the memory (140), the motor driving device (200), etc.

[0092] The motor driving device (200) may be referred to as a motor driving unit as a driving unit for driving the motor (250).

[0093] Meanwhile, the motor driving device (200) includes a plurality of inverter switching elements, an inverter (420) that outputs an AC voltage to the motor (250), an output current detection unit (E) that detects the output current (io) flowing in the motor (250), and current information (id, iq) and a torque command value (T) based on the output current (io) detected by the output current detection unit (E). * ), it may include an inverter control unit (430) that outputs a switching control signal to the inverter (420).

[0094] Meanwhile, current information (id, iq) and torque command (T) based on the output current (io) * ) can be transmitted to an external server (500), and the current command value (i) from the server (500) * d,i * q) may be received. And, based on the current command value received from the communication unit (130), the inverter control unit (430) may output a switching control signal to the inverter (420).

[0095] Accordingly, the motor (250) can be driven based on a current command value corresponding to the maximum torque calculated in real time by the server (500). Therefore, maximum torque driving of the motor (250) becomes possible.

[0096] Meanwhile, the communication unit (130) in the motor drive device (200) transmits current information (id, iq), torque command value (T *), and voltage information regarding the detected DC voltage (Vdc) can be transmitted to the server (500). Accordingly, maximum torque operation of the motor (250) under various conditions becomes possible.

[0097] Meanwhile, the detailed operation of the motor driving device (200) is described with reference to FIG. 3.

[0098] Figure 3 illustrates an example of an internal block diagram of the motor driving device of Figure 2.

[0099] Referring to the drawings, a motor driving device (200) according to an embodiment of the present disclosure is a driving device for driving a motor (250), and may include a plurality of inverter switching elements (Sa to Sc, S'a to S'c), an inverter (420) for outputting an AC voltage to the motor (250), and an inverter control unit (430) for controlling the inverter (420). In addition, the motor driving device (200) may include a memory (270) for providing various stored data to the inverter control unit (430).

[0100] Meanwhile, the motor driving device (200) according to the embodiment of the present disclosure may further include a capacitor (C) that stores the dc voltage (Vdc) that is the input terminal of the inverter (420), a dc voltage detection unit (B) that detects the dc voltage (Vdc), an output current detection unit (E) that detects the output current flowing to the motor (250), and a position detection sensor (105).

[0101] According to an embodiment of the present disclosure, the motor (250) may be a three-phase motor driven by an inverter (420).

[0102] Meanwhile, the inverter control unit (430) sets the current command value (i) corresponding to the calculated maximum torque. * d,i * Based on q), a switching control signal (Sic) can be output to the inverter (420). Accordingly, maximum torque driving of the motor (250) becomes possible.

[0103] The inverter control unit (430) according to the embodiment of the present disclosure provides current information (id, iq) and torque command value (T) in real time. * ) and calculate the torque command value (T * ), the current command value (i * d,i * q) and calculate the current command value (i * d,i * q) is used to drive the motor (250). Accordingly, the accuracy for high-efficiency driving is improved.

[0104] Meanwhile, the motor driving device (200) may further include a capacitor (C) that stores the dc voltage (Vdc) of the input terminal of the inverter (420), and a dc voltage detection unit (B) that detects the dc voltage (Vdc).

[0105] The inverter control unit (430) provides current information (id, iq), torque command value (T * ), and based on the detected dc terminal voltage (Vdc), the current command value (i * d,i * q) and calculate the current command value (i * d,i * q) is used to drive the motor (250). Accordingly, the accuracy for high-efficiency driving is improved.

[0106] Fig. 4 is an example of an internal circuit diagram of the motor driving device of Fig. 3.

[0107] Referring to the drawings, a motor driving device (200) according to an embodiment of the present disclosure may include an inverter (420), an inverter control unit (430), an output current detection unit (E), a dc voltage detection unit (Vdc), and a position detection sensor (105).

[0108] Meanwhile, the motor driving device (200) converts power to drive the motor, so it can also be called a power conversion device.

[0109] The dc capacitor (C) stores the voltage input to the dc terminal (ab terminal). In the drawing, one dc capacitor (C) is illustrated as an element, but multiple capacitors may be provided to ensure element stability.

[0110] Meanwhile, the input voltage supplied to the dc capacitor (C) may be a voltage stored in the battery (205) or a voltage level-converted by a converter (not shown).

[0111] Meanwhile, since both ends of the dc capacitor (C) store direct current voltage, they can also be called dc terminals or dc link terminals.

[0112] The DC voltage detection unit (B) can detect the DC voltage (Vdc) at both ends of the DC capacitor (C). To this end, the DC voltage detection unit (B) can include a resistance element, an amplifier, etc. The detected DC voltage (Vdc) can be input to the inverter control unit (430) as a discrete signal in the form of a pulse.

[0113] The inverter (420) has a plurality of inverter switching elements (Sa to Sc, S'a to S'c), and can convert a direct current voltage (Vdc) into a three-phase alternating current voltage (Va, Vb, Vc) of a predetermined frequency by the on / off operation of the switching elements (Sa to Sc, S'a to S'c), and output it to a three-phase synchronous motor (250).

[0114] The inverter (420) is composed of a pair of upper-arm switching elements (Sa, Sb, Sc) and lower-arm switching elements (S'a, S'b, S'c) that are each connected in series with each other, and a total of three pairs of upper and lower-arm switching elements are connected in parallel with each other (Sa&S'a, Sb&S'b, Sc&S'c). A diode is connected in antiparallel to each switching element (Sa, S'a, Sb, S'b, Sc, S'c).

[0115] The switching elements within the inverter (420) perform on / off operations of each switching element based on the inverter switching control signal (Sic) from the inverter control unit (430). As a result, a three-phase AC voltage having a predetermined frequency is output to the three-phase synchronous motor (250).

[0116] The inverter control unit (430) can control the switching operation of the inverter (420) based on a sensorless method.

[0117] To this end, the inverter control unit (430) can receive the output current (io) detected by the output current detection unit (E).

[0118] The inverter control unit (430) can output an inverter switching control signal (Sic) to each gate terminal of the inverter (420) in order to control the switching operation of the inverter (420). Accordingly, the inverter switching control signal (Sic) may also be referred to as a gate driving signal.

[0119] Meanwhile, the inverter switching control signal (Sic) is a switching control signal of pulse width modulation (PWM) method, and is generated and output based on the output current (io) detected by the output current detection unit (E).

[0120] The output current detection unit (E) detects the output current (io) flowing between the inverter (420) and the three-phase motor (250). That is, the current flowing to the motor (250) can be detected.

[0121] The output current detection unit (E) can detect all output currents (ia, ib, ic) of each phase, or can detect the output currents of two phases using three-phase balance.

[0122] The output current detection unit (E) may be located between the inverter (420) and the motor (250), and a CT (current transformer), shunt resistor, etc. may be used to detect the current.

[0123] The detected output current (io) can be applied to the inverter control unit (430) as a discrete signal in the form of a pulse, and a switching control signal (Sic) is generated based on the detected output current (io).

[0124] The position detection sensor (105) can sense the rotor position information (θ) of the motor (250). The sensed position information (θ) can be input to the inverter control unit (430).

[0125] Meanwhile, a three-phase motor (250) has a stator and a rotor, and an AC voltage of a predetermined frequency is applied to the coils of the stator of each phase (a, b, c phase) to cause the rotor to rotate.

[0126] Such motors (250) may include, for example, a surface-mounted permanent-magnet synchronous motor (SMPMSM), an interior permanent magnet synchronous motor (IPMSM), and a synchronous reluctance motor (Synrm). Among these, SMPMSM and IPMSM are synchronous motors that use permanent magnets (Permanent Magnet Synchronous Motors; PMSM), and Synrm is characterized by not having a permanent magnet.

[0127] Meanwhile, the motor (250) according to the embodiment of the present disclosure is mainly described as an interior permanent magnet synchronous motor (IPMSM).

[0128] Fig. 5 is an example of an internal block diagram of the inverter control unit of Fig. 4.

[0129] Referring to the drawing, the inverter control unit (430) of FIG. 5 can receive the detected output current (io) from the output current detection unit (320) and receive the rotor position information (θ) of the motor (250) from the position detection sensor (105).

[0130] The position detection sensor (105) can detect the magnetic pole position (θ) of the rotor of the motor (250). That is, the position detection sensor (105) can detect the position of the rotor of the motor (250).

[0131] For this purpose, the position detection sensor (105) may include an encoder or a resolver.

[0132] The coordinate system and coordinate axes used are defined here in the following description.

[0133] The αβ coordinate system is a two-dimensional fixed coordinate system with the α and β axes as fixed axes. The α and β axes are orthogonal to each other, and the β axis advances the α axis by an electrical angle of 90˚.

[0134] The dq coordinate system is a two-dimensional rotational coordinate system with the d axis and the q axis as the rotational axis. In a rotational coordinate system that rotates at the same speed as the rotational speed of the magnetic flux created by the permanent magnet of the motor (250), the axis in the direction of the magnetic flux created by the permanent magnet is the d axis, and the axis that is 90 degrees ahead of the d axis in phase is the q axis.

[0135] Referring to FIG. 5, the inverter control unit (430) may include a speed calculation unit (320), an axis conversion unit (310), a torque calculation unit (325), a current command generation unit (330), a voltage command generation unit (340), an axis conversion unit (350), and a switching control signal output unit (360).

[0136] The axis conversion unit (310) within the inverter control unit (430) receives the three-phase output current (ia, ib, ic) detected by the output current detection unit (E) and converts it into a two-phase current (iα, iβ) of the stationary coordinate system.

[0137] Meanwhile, the axis conversion unit (310) can convert the two-phase current (iα, iβ) of the stationary coordinate system into the two-phase current (id, iq) of the rotating coordinate system.

[0138] The speed calculation unit (320) within the inverter control unit (430) estimates the rotor position of the motor (250) based on the two-phase current (iα, iβ) of the stationary coordinate system converted by the axis conversion unit (310). In addition, the calculated speed can be output based on the estimated rotor position.

[0139] The torque calculation unit (325) in the inverter control unit (430) can calculate the current torque (T) based on the calculated speed.

[0140] The current command generation unit (330) in the inverter control unit (430) generates the calculated current torque (T) and the torque command value (T * ), the current command value (i * d,i * q) is generated.

[0141] For example, the current command generation unit (330) generates the calculated current torque (T) and the torque command value (T * ), PI control is performed in the PI controller (335), and the current command value (i * d,i * q) can be generated. Meanwhile, the d-axis current command value (i * The value of d) may be set to 0.

[0142] Meanwhile, the current command generation unit (330) generates a current command value (i * d,i * q) may further include a limiter (not shown) to limit the level so that it does not exceed the allowable range.

[0143] Next, the voltage command generation unit (340) converts the d-axis and q-axis currents (id, iq) converted to a two-phase rotating coordinate system in the axis conversion unit, and the current command value (i) in the current command generation unit (330). * d,i * Based on q), d-axis and q-axis voltage reference values ​​(V* d,V * q) is generated.

[0144] For example, the voltage command generation unit (340) generates a q-axis current (iq) and a q-axis current command value (i * Based on the difference in q), PI control is performed in the PI controller (344), and the q-axis voltage command value (V * q) can be generated. In addition, the voltage command generation unit (340) generates the d-axis current (id) and the d-axis current command value (i * Based on the difference of d), PI control is performed in the PI controller (348), and the d-axis voltage command value (V * d) can be generated. Meanwhile, the d-axis voltage command value (V * The value of d) is the d-axis current command value (i * The value of d) may be set to 0, corresponding to the case where it is set to 0.

[0145] Meanwhile, the voltage command generation unit (340) generates the d-axis and q-axis voltage command values ​​(V * d,V * q) may further include a limiter (not shown) to limit the level so that it does not exceed the allowable range.

[0146] Meanwhile, the generated d-axis and q-axis voltage command values ​​(V * d,V * q) is input to the axis conversion unit (350).

[0147] The axis conversion unit (350) calculates the position calculated in the speed calculation unit (320) and the d-axis and q-axis voltage command values ​​(V * d,V * q) is input and axis transformation is performed.

[0148] First, the axis transformation unit (350) performs a transformation from a two-phase rotational coordinate system to a two-phase stationary coordinate system. At this time, the position calculated by the speed calculation unit (320) can be used.

[0149] And, the axis conversion unit (350) performs a conversion from a two-phase stationary coordinate system to a three-phase stationary coordinate system. Through this conversion, the axis conversion unit (350) obtains a three-phase output voltage command value (V * a,V * b,V * c) will be printed.

[0150] The switching control signal output section (360) outputs a three-phase output voltage command value (V * a,V * b,V * c) A switching control signal (Sic) according to a pulse width modulation (PWM) method can be generated and output.

[0151] The output inverter switching control signal (Sic) is converted into a gate driving signal in a gate driving unit (not shown) and can be input to the gate of each switching element within the inverter (420). As a result, each switching element (Sa, S'a, Sb, S'b, Sc, S'c) within the inverter (420) performs a switching operation.

[0152] FIG. 6 is a diagram illustrating the operation of a battery and an inverter related to the present disclosure.

[0153] Referring to the drawing, when the battery (205h) stores a high voltage of approximately 800 V, when the switching element (SWm) between the battery (205h) and the inverter (420) is turned off as in (a) of FIG. 6 and then turned on as in (b) of FIG. 6, an inrush current (Irs) flows momentarily from the battery (205h) to the capacitor (C) at the on point of the switching element (SWm).

[0154] For example, when a high voltage of approximately 800 V from a battery (205h) is applied while the voltage of the capacitor (C) is discharged and at 0 V, a significantly large inrush current (Irs) occurs, increasing the possibility of damage to the capacitor (C) or inverter (420).

[0155] Accordingly, the present disclosure proposes a method for preventing damage to a capacitor (C) or an inverter (420). In particular, a method is proposed for stably pre-charging the capacitor to lower the level of inrush current. This is described with reference to FIG. 7 and below.

[0156] FIG. 7 is a block diagram illustrating a power conversion device according to an embodiment of the present disclosure.

[0157] Referring to the drawing, a power conversion device (600) according to an embodiment of the present disclosure includes a dc / dc converter (700) that is connected between a first battery (205b) and a second battery (205h) to convert the level of a direct current voltage, and a capacitor (C) that is a dc capacitor.

[0158] Meanwhile, the power conversion device (600) according to the embodiment of the present disclosure further includes an inverter (420) connected to a capacitor (C), which is a DC capacitor.

[0159] Meanwhile, the inverter (420) can operate to drive the motor (250) by converting the direct current voltage into an alternating current voltage based on the voltage of the capacitor (C), which is a dc capacitor.

[0160] Meanwhile, the capacitor (C) and the inverter (420) can correspond to the capacitor (C) and the inverter (420) in the motor driving device (200) of FIG. 3.

[0161] Meanwhile, the power conversion device (600) according to the embodiment of the present disclosure may further include a converter (650) that converts an input AC voltage into a DC voltage. That is, the converter (650) may be an AC / DC converter.

[0162] Meanwhile, the converter (650) can be installed in the vehicle as an on board charger.

[0163] Meanwhile, the second battery (205h) may be placed between the converter (650) and the inverter (420). Specifically, the second battery (205h) may be placed between the converter (650) and the capacitor (C), which is a DC capacitor.

[0164] Meanwhile, the dc / dc converter (700) in the power conversion device (600) according to the embodiment of the present disclosure may be a bidirectional converter.

[0165] For example, the second battery (205h) is a high-voltage battery that can store a high voltage of approximately 800 V, and the first battery (205b) is a low-voltage battery that can store a low voltage of approximately 15 V.

[0166] The power conversion device (600) according to the embodiment of the present disclosure can convert the input AC voltage into a DC voltage by the converter (650) according to the charging mode and store the converted DC voltage in the second battery (205h).

[0167] Meanwhile, the power conversion device (600) according to the embodiment of the present disclosure can store the DC voltage stored in the second battery (205h) in the first battery (205b) in the charging mode.

[0168] At this time, in the charging mode, current can flow from the second battery (205h) toward the first battery (205b), and this current can be called forward current.

[0169] Meanwhile, the power conversion device (600) according to the embodiment of the present disclosure can operate the motor (250) by having the inverter (420) perform a switching operation based on the voltage stored in the second battery (205h) according to the motor driving mode.

[0170] Meanwhile, the power conversion device (600) according to the embodiment of the present disclosure can store regenerative power from the motor (250) in the second battery (205h) through the inverter (420) according to the motor regeneration mode.

[0171] Meanwhile, the power conversion device (600) according to the embodiment of the present disclosure performs a pre-charge mode when the ignition is turned on.

[0172] That is, the power conversion device (600) according to the embodiment of the present disclosure supplies the voltage stored in the first battery (205b) to the capacitor (C), which is a DC capacitor, during the pre-charge mode period.

[0173] In particular, the power conversion device (600) according to the embodiment of the present disclosure, during the pre-charge mode period, does not supply the DC voltage from the second battery (205h) to the capacitor (C), which is a DC capacitor, but supplies the voltage stored in the first battery (205b) to the capacitor (C), which is a DC capacitor. Accordingly, in the pre-charge mode, the capacitor (C) can be stably pre-charged.

[0174] In addition, by pre-charging the capacitor (C) using the voltage stored in the first battery (205b) rather than the DC voltage from the second battery (205h), it is possible to prevent the possibility of damage to the capacitor (C) due to the inrush current.

[0175] Fig. 8 is a drawing illustrating an example of the operation of the power conversion device of Fig. 7.

[0176] Referring to the drawing, the power conversion device (600) of FIG. 7 can supply current from the first battery (205b) toward the second battery (205h) or the capacitor (C) depending on the pre-charge mode. This current (IPC) can be referred to as reverse current.

[0177] Meanwhile, the power conversion device (600) according to the embodiment of the present disclosure may further include a battery switching element (SW) connected between the capacitor (C) and the second battery (205h), as shown in the drawing.

[0178] In the pre-charge mode, the battery switching element (SW) can be turned off, thereby not supplying the DC voltage from the second battery (205h) to the capacitor (C), which is a DC capacitor.

[0179] Meanwhile, in motor drive mode or motor regeneration mode, the battery switching element (SW) can be turned on.

[0180] Meanwhile, in charging mode, it is desirable that the battery switching element (SW) be turned off.

[0181] FIG. 9 is a drawing illustrating an example of a dc / dc converter in the power conversion device of FIG. 7.

[0182] Referring to the drawing, the dc / dc converter (900) according to the embodiment of the present disclosure may be a dc / dc converter (700) in the power conversion device (600) of FIG. 7.

[0183] A dc / dc converter (900) according to an embodiment of the present disclosure comprises a transformer (Tm), a first switching element (M1H) and a second switching element (M1L) arranged on an input side of the transformer (Tm) and connected in series with each other, an inductor (Lm1) connected to one end (nd) of the input side of the transformer (Tm), a third switching element (M2L) and a fourth switching element (M2H) each connected to the other end (nf) of the input side of the transformer (Tm), and a clamp capacitor (CL) connected between the fourth switching element (M2H) and the third switching element (M2L).

[0184] Meanwhile, when the second switching element (M1L) and the fourth switching element (M2H) are turned on, the turn-off timing of the fourth switching element (M2H) is delayed compared to the turn-off timing of the second switching element (M1L). Accordingly, switching loss can be reduced. In particular, switching loss can be reduced by distributing it across multiple switching elements.

[0185] Meanwhile, the dc / dc converter (900) according to the embodiment of the present disclosure may further include an input voltage detection unit (AH) that detects an input voltage (Vin) input to the first switching element (M1H), and a control unit (970) that controls the first to fourth switching elements based on the detected input voltage (Vin).

[0186] Meanwhile, the dc / dc converter (900) according to the embodiment of the present disclosure may further include a first diode (D1) connected to one end of the output side of the transformer (Tm) and a first diode (D1) connected to one end of the output side of the transformer (Tm).

[0187] Referring to the drawing, an input voltage detection unit (AH) can be placed at both ends (na-nc) of the input terminal of the dc / dc converter (900).

[0188] Meanwhile, a first switching element (M1H) may be connected to one end (na) of the input terminal of the dc / dc converter (900), and a second switching element (M1L) may be connected to the other end (nc) of the input terminal of the dc / dc converter (900).

[0189] Meanwhile, a leakage inductor (Lk) may be placed between the node (nb) between the first switching element (M1H) and the second switching element (M1L) that are connected in series with each other and one end (nd) of the input side of the transformer (Tm).

[0190] Meanwhile, a first inductor (Lm1) may be connected to one end (nd) of the input side of the transformer (Tm), and a second inductor (Lm2) may be connected to the other end (nf) of the input side of the transformer (Tm).

[0191] Specifically, a first inductor (Lm1) may be connected between one end (nd) of the input side of the transformer (Tm) and the center tap (ne), and a second inductor (Lm2) may be connected between the other end (nf) of the input side of the transformer (Tm) and the center tap (ne).

[0192] Meanwhile, it is preferable that the inductance of the first inductor (Lm1) be greater than the inductance of the leakage inductor (Lk) on the input side of the transformer (Tm). Accordingly, switching loss can be reduced.

[0193] Meanwhile, a third switching element (M2L) may be placed between the other end (nf) of the input side of the transformer (Tm) and the other end (nc) of the input terminal of the dc / dc converter (900), and a fourth switching element (M2H) may be placed between the other end (nf) of the input side of the transformer (Tm) and one end (ng) of the clamp capacitor (CL).

[0194] Meanwhile, a clamp capacitor (CL) can be connected between the fourth switching element (M2H) and the third switching element (M2L).

[0195] Specifically, one end (ng) of the clamp capacitor (CL) can be connected to the fourth switching element (M2H), and the other end (nh) of the clamp capacitor (CL) can be connected to the third switching element (M2L).

[0196] Meanwhile, the other end (nh) of the clamp capacitor (CL) and the other end (nc) of the input terminal of the dc / dc converter (900) may be the same node.

[0197] Meanwhile, a first diode (D1) may be connected to one end (ni) of the output side of the transformer (Tm), and a second diode (D2) may be connected to the other end (nk) of the output side of the transformer (Tm).

[0198] Specifically, the anode of the first diode (D1) can be connected to one end (ni) of the output side of the transformer (Tm), and the anode of the second diode (D2) can be connected to the other end (nk) of the output side of the transformer (Tm).

[0199] Meanwhile, the cathode of the first diode (D1) and the cathode of the first diode (D1) can each be connected to one end (nm) of the output capacitor (Co).

[0200] Meanwhile, the other end of the output capacitor (Co) can be connected to the center tap (nj) on the output side of the transformer (Tm).

[0201] Meanwhile, an output resistor (Ro) can be connected between the two terminals (nm-nj) of the output capacitor (Co).

[0202] Meanwhile, the dc / dc converter (900) of FIG. 9 may be named a dual switching element active clamp forward flyback converter (DS-ACFF: Dual Switch Active Clamp Forward Flyback converter).

[0203] Meanwhile, the control unit (970) can output a pulse width modulation (PWM)-based gate signal or switching control signal to each of the first to fourth switching elements.

[0204] Meanwhile, the control unit (970) can vary the turn-on duty of the second switching element (M1L) or the turn-on duty of the fourth switching element (M2H) based on the level of the input voltage (Vin). Accordingly, switching loss can be reduced.

[0205] FIG. 10a illustrates an example of an operating waveform of a dc / dc converter related to the present disclosure.

[0206] Referring to the drawing, (a) of FIG. 10a shows a switching control signal (GRxa) of the fourth switching element (M2H) and a switching control signal (GRxb) of the third switching element (M2L).

[0207] Figure 10a (b) shows the switching control signal (GRxc) of the second switching element (M1L) and the switching control signal (GRxd) of the first switching element (M1H).

[0208] According to FIG. 10a, the second switching element (M1L) and the fourth switching element (M2H) can be turned on and off synchronously, and the first switching element (M1H) and the third switching element (M2L) can be turned on and off synchronously.

[0209] Specifically, when the level of the switching control signal (GRxc, GRxa) of the second switching element (M1L) and the fourth switching element (M2H) is a high level (LV1), it is turned on, and when it is switched to a low level (LV2) at time T1x, it is turned off at time T1x.

[0210] Meanwhile, at a time point T2x, which is a predetermined time (Pxa) after the turn-off time point (T1x) of the second switching element (M1L) and the fourth switching element (M2H), when the level of the switching control signal (GRxc, GRxa) of the first switching element (M1H) and the third switching element (M2L) switches from a low level (LV2) to a high level (LV1), the first switching element (M1H) and the third switching element (M2L) are turned on at a time point T2x.

[0211] Figure 10a (c) shows the voltage waveform (GRxe) across the first switching element (M1H) and the voltage waveform (GRxf) across the third switching element (M2L).

[0212] Referring to the drawing, until time T1x, the voltage across the first switching element (M1H) is LV3, and the voltage across the third switching element (M2L) is maintained at LV4, which is lower than LV3, and then decreases between time T1x and time Tx2.

[0213] Meanwhile, at the time point Tx2, when the first switching element (M1H) and the third switching element (M2L) are turned on, hard switching is performed because the voltage across the first switching element (M1H) has not yet dropped to 0 V. Accordingly, there are disadvantages such as significant switching loss and heat generation.

[0214] (d) of Fig. 10a shows the voltage waveform (GRxg) across the two ends of the second switching element (M1L) and the voltage waveform (GRxh) across the three switching elements (M2L).

[0215] Referring to the drawing, until time T1x, the voltage waveform at both ends of the third switching element (M2L) is maintained at LV5, and then decreases between time T1x and time Tx2.

[0216] Meanwhile, until the T1x time point, the voltage across the two terminals of the second switching element (M1L) is maintained at LV6, which is lower than LV5, and then increases between the T1x time point and the Tx2 time point.

[0217] Meanwhile, at the time point Tx2, when the first switching element (M1H) and the third switching element (M2L) are turned on, hard switching is performed because the voltage across the first switching element (M1H) is a high voltage rather than 0 V. Accordingly, there are disadvantages such as significant switching loss and heat generation.

[0218] Accordingly, in this disclosure, unlike the method of Fig. 10a, a method for reducing switching loss is proposed. This is described with reference to Fig. 10b and the like.

[0219] FIG. 10b illustrates an example of an operating waveform of a dc / dc converter according to an embodiment of the present disclosure.

[0220] Referring to the drawing, (a) of FIG. 10b shows a switching control signal (GRaa) of the fourth switching element (M2H) and a switching control signal (GRab) of the third switching element (M2L).

[0221] Figure 10b (b) shows the switching control signal (GRac) of the second switching element (M1L) and the switching control signal (GRad) of the first switching element (M1H).

[0222] According to Fig. 10b, the turn-off timings of the second switching element (M1L) and the fourth switching element (M2H) are different. In particular, the turn-off timing (Ta2) of the fourth switching element (M2H) is delayed compared to the turn-off timing (Ta1) of the second switching element (M1L).

[0223] In the drawing, it is illustrated that the turn-off time (Ta2) of the fourth switching element (M2H) is delayed by the period Pa1 compared to the turn-off time (Ta1) of the second switching element (M1L).

[0224] Specifically, when the level of the switching control signal (GRaa, GRac) of the second switching element (M1L) and the fourth switching element (M2H) is a high level (LV1), it is turned on, and at the time Ta1, the level of the switching control signal (Grac) of the second switching element (M1L) can be switched from a high level (LV1) to a low level (LV2).

[0225] Accordingly, at time Ta1, the second switching element (M1L) is turned off, and the fourth switching element (M2H) remains turned on.

[0226] Meanwhile, at the Ta2 time point after the Ta1 time point, the level of the switching control signal (GRaa) of the fourth switching element (M2H) can be switched from a high level (LV1) to a low level (LV2).

[0227] Accordingly, at time Ta2, the second switching element (M1L) is turned off, and the fourth switching element (M2H) is also turned off.

[0228] Meanwhile, according to FIG. 10b, the turn-on timings of the first switching element (M1H) and the third switching element (M2L) are different. In particular, the turn-on timing (Ta3) of the third switching element (M2L) is delayed compared to the turn-on timing (Ta2) of the first switching element (M1H).

[0229] Specifically, when the level of the switching control signal (GRad, GRab) of the first switching element (M1H) and the third switching element (M2L) is a low level (LV2), it is turned off, and at the time Ta2, the level of the switching control signal (Grad) of the first switching element (M1H) can be switched from a low level (LV2) to a high level (LV1).

[0230] Accordingly, at time Ta2, the first switching element (M1H) is turned on, and the third switching element (M2L) continues to be turned off.

[0231] Meanwhile, at the Ta3 time point after the Ta2 time point, the level of the switching control signal (GRab) of the third switching element (M2L) can be switched from a low level (LV2) to a high level (LV1).

[0232] Accordingly, at time Ta3, the first switching element (M1H) is turned on, and the third switching element (M2L) is also turned on.

[0233] Figure 10b (c) shows the voltage waveform (GRae) across the first switching element (M1H) and the voltage waveform (GRaf) across the third switching element (M2L).

[0234] Referring to the drawing, until the Ta1 point, the voltage across the first switching element (M1H) is LV3, and the voltage across the third switching element (M2L) is maintained at LV4, which is lower than LV3.

[0235] Meanwhile, at time Ta1, the second switching element (M1L) is turned off and the fourth switching element (M2H) remains turned on, so the voltage across the first switching element (M1H) decreases from time Ta1 to time Ta2.

[0236] At approximately Ta2 time, the voltage across the first switching element (M1H) may be OV or a voltage close to OV.

[0237] Meanwhile, the voltage across the third switching element (M2L) can be maintained at LV4 from the Ta1 point to the Ta3 point, and then maintained at 0 V after the Ta3 point.

[0238] Meanwhile, at time Ta2, when the first switching element (M1H) is turned on, the voltage across the first switching element (M1H) is 0V or a voltage close to 0V, so zero voltage switching or valley switching can be performed. Accordingly, switching loss during switching of the first switching element (M1H) can be reduced.

[0239] (d) of Fig. 10b shows the voltage waveform (GRag) across the two terminals of the second switching element (M1L) and the voltage waveform (GRah) across the three switching elements (M2L).

[0240] Referring to the drawing, until the Ta1 point, the voltage across the second switching element (M1L) is LV6, and the voltage across the fourth switching element (M2H) is maintained at LV5, which is higher than LV6.

[0241] Meanwhile, at time Ta1, the second switching element (M1L) is turned off and the fourth switching element (M2H) remains turned on, so the voltage across the second switching element (M1L) increases from time Ta1 to time Ta2.

[0242] At approximately Ta2 time, the voltage across the first switching element (M1H) may be LV3 or a voltage close to LV3.

[0243] Meanwhile, the voltage waveform at both ends of the third switching element (M2L) can maintain LV5 from the Ta1 point to the Ta3 point, and then maintain 0 V after the Ta3 point.

[0244] Meanwhile, at the Ta1 time point, when the second switching element (M1L) is turned off, the voltage across the second switching element (M1L) is LV6, which is OV or a voltage close to OV, so zero voltage switching can be performed. Accordingly, switching loss during switching of the second switching element (M1L) can be reduced.

[0245] Meanwhile, the control unit (970) can control the delay period (Pa1) of the delay to increase as the level of the input voltage (Vin) increases. Accordingly, switching loss can be reduced.

[0246] Meanwhile, the control unit (970) can control the turn-on duty of the first switching element (M1H) or the turn-on duty of the third switching element (M2L) to increase as the level of the input voltage (Vin) decreases. Accordingly, switching loss can be reduced.

[0247] Meanwhile, the control unit (970) can turn on the first switching element (M1H) after the delay-off of the fourth switching element (M2H). Accordingly, switching loss can be reduced.

[0248] Meanwhile, the control unit (970) can turn on the first switching element (M1H) after the delay-off of the fourth switching element (M2H), and can turn on the third switching element (M2L) after the turn-on of the first switching element (M1H). Accordingly, switching loss can be reduced.

[0249] Figures 11a to 11g are drawings referenced in the description of Figure 10a.

[0250] Figure 11a illustrates the current path by Mode 1 operation of the dc / dc converter related to the present disclosure.

[0251] Referring to the drawing, based on Mode 1, the first switching element (M1H) and the third switching element (M2L) can be turned on.

[0252] Accordingly, input current can flow to the first switching element (M1H), leakage inductor (Lk), input side of transformer (Tm), and third switching element (M2L), and output current can flow to the output side of transformer (Tm), first diode (D1), output capacitor (Co), and output resistor (Ro).

[0253] Figure 11b illustrates the current path by Mode 2 operation of the dc / dc converter related to the present disclosure.

[0254] Referring to the drawing, based on Mode 2, the first switching element (M1H) and the third switching element (M2L) can be turned off.

[0255] Accordingly, a portion of the input current may flow to the parasitic capacitor of the first switching element (M1H), the leakage inductor (Lk), the input side of the transformer (Tm), and the parasitic capacitor of the third switching element (M2L). In addition, another portion of the input current may flow to the parasitic capacitor of the second switching element (M1L), and another portion of the input current may flow to the parasitic capacitor of the fourth switching element (M2H).

[0256] Meanwhile, output current can flow through the output side of the transformer (Tm), the first diode (D1), the output capacitor (Co), and the output resistor (Ro).

[0257] Figure 11c illustrates the current path by Mode 3 operation of the dc / dc converter related to the present disclosure.

[0258] Referring to the drawing, based on Mode 3, the first switching element (M1H) and the third switching element (M2L) can be continuously turned off.

[0259] Accordingly, the input current path can be the same as in Fig. 11b.

[0260] Meanwhile, a portion of the output current may flow through one end (ni) of the output side of the transformer (Tm), the first diode (D1), the output capacitor (Co), and the output resistor (Ro), and another portion of the output current may flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0261] Figure 11d illustrates the current path by Mode 4 operation of the dc / dc converter related to the present disclosure.

[0262] Referring to the drawing, based on Mode 4, the second switching element (M1L) and the fourth switching element (M2H) can be turned on.

[0263] Accordingly, input current can flow to the output capacitor (Co), the fourth switching element (M2H), the input side of the transformer (Tm), the leakage inductor (Lk), and the second switching element (M1L).

[0264] Meanwhile, output current can flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0265] FIG. 11e illustrates the current path by Mode 5 operation of the dc / dc converter related to the present disclosure.

[0266] Referring to the drawing, based on Mode 5, the second switching element (M1L) and the fourth switching element (M2H) can be turned off.

[0267] Accordingly, a portion of the input current may flow to the output capacitor (Co), the parasitic capacitor of the fourth switching element (M2H), the input side of the transformer (Tm), the leakage inductor (Lk), and the parasitic capacitor of the first switching element (M1H).

[0268] Additionally, another portion of the input current may flow to the parasitic capacitor of the second switching element (M1L), and another portion of the input current may flow to the parasitic capacitor of the third switching element (M2L).

[0269] Meanwhile, output current can flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0270] Meanwhile, when operating in Mode 5, the voltage across the first switching element (M1H) and the voltage across the third switching element (M2L) can be lowered by the first inductor (Lm1).

[0271] FIG. 11f illustrates the current path by Mode 6 operation of the dc / dc converter related to the present disclosure.

[0272] Referring to the drawing, based on Mode 6, the second switching element (M1L) and the fourth switching element (M2H) can be continuously turned off.

[0273] Accordingly, the input current path can be the same as in Fig. 11e.

[0274] Meanwhile, a portion of the output current may flow through one end (ni) of the output side of the transformer (Tm), the first diode (D1), the output capacitor (Co), and the output resistor (Ro), and another portion of the output current may flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0275] Meanwhile, when operating in Mode 6, the voltage across the first switching element (M1H) and the voltage across the third switching element (M2L) may drop due to the leakage inductor (Lk). At this time, the current peak of the current flowing through the leakage inductor (Lk) may be iLkmin.

[0276] FIG. 11g illustrates each signal waveform related to the present disclosure.

[0277] Referring to the drawing, (a) of FIG. 11g illustrates a signal waveform (GRya) in which the first switching element (M1H) and the third switching element (M2L) are synchronously turned on and off, and the second switching element (M1L) and the fourth switching element (M2H) are synchronously turned on and off.

[0278] That is, each signal waveform (GRya) of (a) of Fig. 11g can correspond to Mode 1 to Mode 6 of Figs. 11a to 11f.

[0279] For example, during the DTs period, the first switching element (M1H) and the third switching element (M2L) can be synchronously turned on, and during the (1-D)Ts period, the second switching element (M1L) and the fourth switching element (M2H) can be synchronously turned on.

[0280] Specifically, the first switching element (M1H) and the third switching element (M2L) can be synchronously turned on from Tox to T1x, and the first switching element (M1H) and the third switching element (M2L) can be synchronously turned off from T2x to T3x.

[0281] Meanwhile, the second switching element (M1L) and the fourth switching element (M2H) can be synchronously turned on from T3x to T4x, and the second switching element (M1L) and the fourth switching element (M2H) can be synchronously turned off from T4x to T6x.

[0282] Figure 11g (b) illustrates the waveform (GRyb) of the voltage across the four terminals of the fourth switching element (M2H) and the waveform (GRyc) of the voltage across the three terminals of the third switching element (M2L).

[0283] Figure 11g (c) illustrates the waveform (GRyd) of the voltage across the two terminals of the second switching element (M1L) and the waveform (GRye) of the voltage across the two terminals of the first switching element (M1H).

[0284] (d) of Fig. 11g illustrates the waveform (GRyf) of the current (iLm2) flowing in the second inductor (Lm2) and the waveform (GRyg) of the current (iLm1) flowing in the first inductor (Lm1).

[0285] Meanwhile, the peak value (iLm2max) of the current (iLm2) flowing in the second inductor (Lm2) may be equal to the peak value (iLkmax) of the current flowing in the leakage inductor (Lk).

[0286] Meanwhile, the minimum value (iLm1min) of the current (iLm1) flowing in the first inductor (Lm1) may be equal to the minimum value (iLkmin) of the current flowing in the leakage inductor (Lk).

[0287] That is, there is a disadvantage in that the energy stored in the leakage inductor (Lk) is small, making zero voltage switching or zero current switching of the first switching element (M1H) and the third switching element (M2L) difficult.

[0288] Meanwhile, the following mathematical equations 1-1 and 1-2 represent the current peak of the leakage inductor (Lk) when the voltage across both ends of each switching element decreases.

[0289] [Mathematical Formula 1-1]

[0290]

[0291] [Equation 1-2]

[0292]

[0293] Figure 12a illustrates each signal waveform when the turn-on duty of a switching element related to the present disclosure is greater than or equal to a first reference value. The first reference value at this time may be approximately 0.67.

[0294] Referring to the drawing, (a) of FIG. 12a illustrates a signal waveform (GRya) in which the first switching element (M1H) and the third switching element (M2L) are synchronously turned on and off, and the second switching element (M1L) and the fourth switching element (M2H) are synchronously turned on and off.

[0295] According to the signal waveform (GRya), at time t4x, the second switching element (M1L) and the fourth switching element (M2H) are turned off, and at time t6x, the first switching element (M1H) and the third switching element (M2L) are turned on.

[0296] Figure 12a (b) illustrates the waveform (GRyb) of the voltage across the first switching element (M1H) and the waveform (GRyc) of the voltage across the third switching element (M2L).

[0297] For example, the voltage across the third switching element (M2L) maintains the clamp voltage (Vcl) and then decreases from time t4x to time t6x, and may be lower than the input voltage (Vin) at time t6x.

[0298] In particular, at time t5x, which is between time t4x and time t6x, the voltage across the third switching element (M2L) may be the input voltage (Vin).

[0299] Meanwhile, the voltage at both ends of the first switching element (M1H) maintains an input voltage (Vin) lower than the clamp voltage (Vcl), then decreases from the time point t4x, and can maintain a certain level before the time point tx5.

[0300] (c) of Fig. 12a illustrates the waveform (GRyd) of the voltage across the two terminals of the second switching element (M1L) and the waveform (GRye) of the voltage across the three switching elements (M2L).

[0301] For example, the voltage across the third switching element (M2L) maintains the clamp voltage (Vcl) and then decreases from time t4x to time t6x, and may be lower than the input voltage (Vin) at time t6x.

[0302] Meanwhile, the voltage across the second switching element (M1L) increases from time t4x and can maintain the input voltage (Vin) from time t5x.

[0303] (d) of Fig. 12a illustrates the waveform (GRyf) of the current (iLm2) flowing in the second inductor (Lm2) and the waveform (GRyg) of the current (iLm1) flowing in the first inductor (Lm1).

[0304] The current (iLm2) flowing in the second inductor (Lm2) sequentially decreases, and then increases again from the time point tx6.

[0305] The current (iLm1) flowing in the first inductor (Lm1) sequentially decreases, and then increases again from the time point tx5.

[0306] Referring to Fig. 12a, when the second switching element (M1L) and the fourth switching element (M2H), which are sub-switching elements, are turned off, the voltage across the first switching element (M1H) and the voltage across the third switching element (M2L) can be lowered simultaneously by the energy of the first inductor (Lm1) in Mode 5.

[0307] Meanwhile, the voltage across the first switching element (M1H) can be lowered to 0 V in Mode 5, and the voltage across the third switching element (M2L) can be lowered to an input voltage (Vin) that is equal to the voltage across the second switching element (M1L).

[0308] In Mode 6, the voltage across the third switching element (M2L) can be lowered only by the energy of the leakage inductor (Lk).

[0309] At this time, the voltage across the first switching element (M1H) is 0 V, and the voltage across the third switching element (M2L) can be lowered as in mathematical expression 2.

[0310] [Equation 2]

[0311]

[0312] Figure 12b illustrates each signal waveform when the turn-on duty of the switching element related to the present disclosure is between a first reference value and a second reference value. In this case, the first reference value may be approximately 0.67, and the second reference value may be approximately 0.5.

[0313] Referring to the drawing, the signal waveform (GRya) of (a) of Fig. 12b is, like the signal waveform (GRya) of (a) of Fig. 12a, at time t4x, the second switching element (M1L) and the fourth switching element (M2H) are turned off, and at time t6x, the first switching element (M1H) and the third switching element (M2L) are turned on.

[0314] (b) of Fig. 12b illustrates the waveform (GRyb) of the voltage across the first switching element (M1H) and the waveform (GRyc) of the voltage across the third switching element (M2L).

[0315] For example, the voltage across the third switching element (M2L) maintains the clamp voltage (Vcl) and then decreases from the time t4x to the time t6x, and at the time t6x, it may be lower than the voltage Vin-Vcl / 2.

[0316] In particular, at time t5x, which is between time t4x and time t6x, the voltage across the third switching element (M2L) may be the Vin-Vcl / 2 voltage.

[0317] Meanwhile, the voltage across the first switching element (M1H) may maintain an input voltage (Vin) lower than the clamp voltage (Vcl) and then decrease from the time point t4x to the time point t6x. The voltage across the first switching element (M1H) at the time point tx6 may be lower than the voltage Vin-Vcl / 2.

[0318] (c) of Fig. 12b illustrates the waveform (GRyd) of the voltage across the two terminals of the second switching element (M1L) and the waveform (GRye) of the voltage across the three switching elements (M2L).

[0319] For example, the voltage across the third switching element (M2L) maintains the clamp voltage (Vcl) and then decreases from time t4x to time t6x, and may be lower than Vcl / 2 at time t6x. In particular, the voltage may be Vcl / 2 at time tx5.

[0320] Meanwhile, the voltage at both ends of the second switching element (M1L) increases from the time point t4x, and can maintain a voltage greater than the Vcl / 2 voltage between the time points t5x and t6x.

[0321] Figure 12b (d) illustrates the waveform (GRyf) of the current (iLm2) flowing in the second inductor (Lm2) and the waveform (GRyg) of the current (iLm1) flowing in the first inductor (Lm1).

[0322] The current (iLm2) flowing in the second inductor (Lm2) sequentially decreases, and then increases again from the time point tx6.

[0323] The current (iLm1) flowing in the first inductor (Lm1) sequentially decreases, and then increases again from the time point tx5.

[0324] Referring to Fig. 12b, in Mode 5, the voltage across the first switching element (M1H) and the voltage across the third switching element (M2L) decrease due to the energy of the first inductor (Lm1), and the voltage across the third switching element (M2L) decreases to Vcl / 2, which is equal to the voltage across the second switching element (M1L), and the voltage across the first switching element (M1H) can decrease to the voltage Vin-Vcl / 2.

[0325] In Mode 6, the voltage across the first switching element (M1H) and the voltage across the third switching element (M2L) can be lowered only by the leakage inductor (Lk).

[0326] Meanwhile, the voltage at both ends of each switching element can be lowered as in mathematical expression 3.

[0327] [Equation 3]

[0328]

[0329] Figure 12c illustrates each signal waveform when the turn-on duty of the switching element related to the present disclosure is less than the second reference value. The second reference value at this time may be approximately 0.5.

[0330] Referring to the drawing, the signal waveform (GRya) of (a) of Fig. 12c is, like the signal waveform (GRya) of (a) of Fig. 12a, that at time t4x, the second switching element (M1L) and the fourth switching element (M2H) are turned off, and at time t6x, the first switching element (M1H) and the third switching element (M2L) are turned on.

[0331] Figure 12c (b) illustrates the waveform (GRyb) of the voltage across the first switching element (M1H) and the waveform (GRyc) of the voltage across the third switching element (M2L).

[0332] For example, the voltage across the first switching element (M1H) maintains the input voltage (Vin) and then decreases from the time point t4x to the time point t6x, and at the time point t6x, it may be lower than the voltage Vin-Vcl / 2.

[0333] In particular, at time t5x, which is between time t4x and time t6x, the voltage across the first switching element (M1H) may be the Vin-Vcl / 2 voltage.

[0334] Meanwhile, the voltage across the third switching element (M2L) may maintain a clamp voltage (Vcl) lower than the input voltage (Vin) and then decrease from the time t4x to the time t6x. The voltage across the third switching element (M2L) at the time tx6 may be lower than the voltage Vin-Vcl / 2.

[0335] (c) of Fig. 12c illustrates the waveform (GRyd) of the voltage across the two terminals of the second switching element (M1L) and the waveform (GRye) of the voltage across the two terminals of the third switching element (M2L).

[0336] For example, the voltage across the third switching element (M2L) maintains the clamp voltage (Vcl) and then decreases from time t4x to time t6x, and may be lower than Vcl / 2 at time t6x. In particular, the voltage may be Vcl / 2 at time tx5.

[0337] Meanwhile, the voltage across the second switching element (M1L) increases from the time point t4x to the time point t6x, and may be Vcl / 2 voltage at the time point t5x.

[0338] Figure 12c (d) illustrates the waveform (GRyf) of the current (iLm2) flowing in the second inductor (Lm2) and the waveform (GRyg) of the current (iLm1) flowing in the first inductor (Lm1).

[0339] The current (iLm2) flowing in the second inductor (Lm2) sequentially decreases, and then increases again from the time point tx6.

[0340] The current (iLm1) flowing in the first inductor (Lm1) sequentially decreases, and then increases again from the time point tx5.

[0341] Referring to Fig. 12c, in Mode 5, the voltage across the first switching element (M1H) can be lowered to the voltage Vin-Vcl / 2, and the voltage across the third switching element (M2L) can be lowered to the voltage Vcl / 2.

[0342] In Mode 6, the voltage across the first switching element (M1H) and the voltage across the third switching element (M2L) can be lowered only by the energy of the leakage inductor (Lk). At this time, the voltage across the two terminals of each switching element can be lowered as shown in the above mathematical expression 3.

[0343] Meanwhile, according to FIGS. 12a to 12c, there is a disadvantage in that hard switching occurs, particularly in Mode 5 and Mode 6, resulting in significant switching loss.

[0344] Accordingly, in this disclosure, a method is proposed in which zero voltage switching or valley switching is performed instead of hard switching.

[0345] FIG. 13a illustrates a current path by Mode 1 operation of a dc / dc converter according to an embodiment of the present disclosure.

[0346] Referring to the drawing, the control unit (970) can turn on the first switching element (M1H) and the third switching element (M2L), which are main switching elements, based on Mode 1.

[0347] Accordingly, input current can flow to the first switching element (M1H), leakage inductor (Lk), input side of transformer (Tm), and third switching element (M2L), and output current can flow to the output side of transformer (Tm), first diode (D1), output capacitor (Co), and output resistor (Ro).

[0348] FIG. 13b illustrates the current path by Mode 2 operation of the dc / dc converter according to an embodiment of the present disclosure.

[0349] Referring to the drawing, the control unit (970) can turn off the first switching element (M1H) and the third switching element (M2L) based on Mode 2.

[0350] Accordingly, a portion of the input current may flow to the parasitic capacitor of the first switching element (M1H), the leakage inductor (Lk), the input side of the transformer (Tm), and the parasitic capacitor of the third switching element (M2L). In addition, another portion of the input current may flow to the parasitic capacitor of the second switching element (M1L), and another portion of the input current may flow to the parasitic capacitor of the fourth switching element (M2H).

[0351] Meanwhile, output current can flow through the output side of the transformer (Tm), the first diode (D1), the output capacitor (Co), and the output resistor (Ro).

[0352] Meanwhile, in Mode 2 operation, the voltage across the two terminals of the second switching element (M1L), which is a sub-switching element, and the voltage across the four switching elements (M2H) can be lowered by the second inductor (Lm2).

[0353] FIG. 13c illustrates the current path by Mode 3 operation of the dc / dc converter according to an embodiment of the present disclosure.

[0354] Referring to the drawing, the control unit (970) can continuously turn off the first switching element (M1H) and the third switching element (M2L) based on Mode 3.

[0355] Accordingly, the input current path can be the same as in Fig. 13b.

[0356] Meanwhile, a portion of the output current may flow through one end (ni) of the output side of the transformer (Tm), the first diode (D1), the output capacitor (Co), and the output resistor (Ro), and another portion of the output current may flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0357] Meanwhile, in Mode 3 operation, the voltage across the second switching element (M1L) and the voltage across the fourth switching element (M2H) may drop due to the leakage inductor (Lk). At this time, the current peak of the current flowing in the leakage inductor (Lk) may be iLkmax.

[0358] FIG. 13d illustrates the current path by Mode 4 operation of the dc / dc converter according to an embodiment of the present disclosure.

[0359] Referring to the drawing, the control unit (970) can turn on the second switching element (M1L) and the fourth switching element (M2H), which are sub-switching elements, based on Mode 4.

[0360] Accordingly, input current can flow to the output capacitor (Co), the fourth switching element (M2H), the input side of the transformer (Tm), the leakage inductor (Lk), and the second switching element (M1L).

[0361] Meanwhile, output current can flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0362] In summary of FIGS. 13a to 14d, as in FIG. 13a, during the first period, current can flow through the first diode (D1) based on the turn-on of the first switching element (M1H) and the third switching element (M2L).

[0363] Meanwhile, after the first period, as shown in FIG. 13d, current can flow through the second diode (D2) based on the turn-on of the second switching element (M1L) and the fourth switching element (M2H).

[0364] Figures 14a to 14c illustrate the operation of Mode 5, Mode 5-1, and Mode 6 when the turn-on duty is equal to or greater than the reference value or when the level of the input voltage (Vin) is equal to or less than the level of the voltage (Vcl) of the clamp capacitor (CL).

[0365] FIG. 14a illustrates a current path by Mode 5 operation of a dc / dc converter according to an embodiment of the present disclosure.

[0366] Referring to the drawing, the control unit (970) can control the second switching element (M1L) to be turned off and the fourth switching element (M2H) to be delayed without being turned off based on Mode 5.

[0367] That is, the control unit (970) can control the second switching element (M1L) to be turned off and the fourth switching element (M2H) to be turned on based on Mode 5.

[0368] Accordingly, a portion of the input current may flow to the output capacitor (Co), the fourth switching element (M2H), the input side of the transformer (Tm), the leakage inductor (Lk), and the parasitic capacitor of the first switching element (M1H).

[0369] Additionally, another portion of the input current may flow to the parasitic capacitor of the second switching element (M1L).

[0370] Meanwhile, output current can flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0371] Meanwhile, by the Mode 5 operation, the voltage across the first switching element (M1H) can be lowered to 0 V through the first inductor (Lm1).

[0372] FIG. 14b illustrates the current path by Mode 5-1 operation of the dc / dc converter according to an embodiment of the present disclosure.

[0373] Referring to the drawing, the control unit (970) can control the second switching element (M1L) to be turned off, the fourth switching element (M2H) to be turned off, and the first switching element (M1H) to be turned on based on Mode 5-1.

[0374] Accordingly, input current can flow to the input side of the first switching element (M1H), the leakage inductor (Lk), the transformer (Tm), the parasitic capacitor of the fourth switching element (M2H), and the parasitic capacitor of the third switching element (M2L).

[0375] Meanwhile, output current can flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0376] Meanwhile, since the fourth switching element (M2H) is turned off by the Mode 5-1 operation, the voltage across the third switching element (M2L) can be lowered to the input voltage (Vin) by the first inductor (Lm1) until the voltage across the second switching element (M1L) and the voltage across the third switching element (M2L) become equal.

[0377] FIG. 14c illustrates the current path by Mode 6 operation of the dc / dc converter according to an embodiment of the present disclosure.

[0378] Referring to the drawing, the control unit (970) can control the second switching element (M1L) to be turned off, the fourth switching element (M2H) to be turned off, and the first switching element (M1H) to be continuously turned on based on Mode 6.

[0379] Accordingly, input current can flow to the input side of the first switching element (M1H), the leakage inductor (Lk), the transformer (Tm), the parasitic capacitor of the fourth switching element (M2H), and the parasitic capacitor of the third switching element (M2L).

[0380] Meanwhile, a portion of the output current may flow through one end (ni) of the output side of the transformer (Tm), the first diode (D1), the output capacitor (Co), and the output resistor (Ro), and another portion of the output current may flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0381] Meanwhile, by mode 6 operation, the voltage across the third switching element (M2L) is lowered through the leakage inductor (Lk), enabling valley switching. Meanwhile, the valley switching timing can be determined according to the turn-on duty (D).

[0382] At this time, the voltages at both ends of the first switching element (M1H) and the voltages at both ends of the third switching element (M2L) are as shown in mathematical expression 4.

[0383] [Equation 4]

[0384]

[0385] In summary of FIGS. 14a to 14c, when the turn-on duty of the second switching element (M1L) or the turn-on duty of the fourth switching element (M2H) is equal to or greater than a reference value, the turn-off timing of the fourth switching element (M2H) is delayed compared to the turn-off timing of the second switching element (M1L), and current can flow in the second diode (D2) based on the turn-off of the second switching element (M1L) and the turn-on of the fourth switching element (M2H). Accordingly, switching loss can be reduced.

[0386] Meanwhile, based on the turn-on of the first switching element (M1H), current flows only through the second diode (D2), and then can flow through the first diode (D1) and the second diode (D2), respectively. Accordingly, switching loss can be reduced.

[0387] Figure 15a describes the operation of Mode 4, Mode 5, Mode 5-1, and Mode 6 when the turn-on duty is above a reference value or when the level of the input voltage (Vin) is below the level of the voltage (Vcl) of the clamp capacitor (CL).

[0388] Referring to the drawing, in Mode 4, the second switching element (M1L) and the fourth switching element (M2H) are turned on, and in Mode 5, only the second switching element (M1L) is turned off and the turn-off of the fourth switching element (M2H) is delayed.

[0389] Next, in Mode 5-1, only the first switching element (M1H) is turned on, and in Mode 6, only the first switching element (M1H) is turned on.

[0390] Meanwhile, in Mode 6, the third switching element (M2L) can perform valley switching.

[0391] Figure 15b is a drawing referenced in the description of Figure 15a.

[0392] Referring to the drawing, GRba represents a switching control signal of the fourth switching element (M2H), and GRbb represents a switching control signal of the second switching element (M1L).

[0393] When the second switching element (M1L) and the fourth switching element (M2H) are turned on, at time t4, the second switching element (M1L) is turned off first, and the turn-off point of the fourth switching element (M2H) is delayed to time t5.

[0394] Meanwhile, at time t5, the first switching element (M1H) may be turned on, and at time t7, the third switching element (M2L) may be turned on.

[0395] Grbc may be a waveform of voltage across the two terminals of the third switching element (M2L), Grbd may be a waveform of voltage across the two terminals of the first switching element (M1H), Grbe may be a waveform of voltage across the three switching elements (M2L), and Grbf may be a waveform of voltage across the two terminals of the second switching element (M1L).

[0396] At time t4, the voltage across the first switching element (M1H) decreases from the input voltage (Vin), and the voltage across the first switching element (M1H) can maintain a constant voltage before time t5.

[0397] At time t5, the voltage across the third switching element (M2L) and the voltage across the second switching element (M1L) begin to decrease from the clamp voltage (Vcl) and can continue to decrease until time t7.

[0398] Meanwhile, at time t6, the voltage across the third switching element (M2L) and the voltage across the second switching element (M1L) may be the input voltage (Vin).

[0399] At time t4, the voltage across the second switching element (M1L) increases, so that a constant voltage can be maintained before time t5.

[0400] GRbg may represent the waveform of the current (iLm2) flowing in the second inductor (Lm2), and GRbh may represent the waveform of the current (iLm1) flowing in the first inductor (Lm1).

[0401] The current (iLm2) flowing in the second inductor (Lm2) may sequentially decrease and then increase again from time t7.

[0402] The current (iLm1) flowing in the first inductor (Lm1) sequentially decreases, and then increases again from time t6.

[0403] Meanwhile, at the end point of the delay (t5), the voltage across the third switching element (M2L) may be equal to the voltage (Vcl) of the clamp capacitor (CL).

[0404] In summary of FIGS. 14A to 15B, when the turn-on duty of the first switching element (M1H) or the turn-on duty of the third switching element (M2L) is equal to or greater than a reference value, or when the level of the input voltage (Vin) is equal to or less than the level of the voltage (Vcl) of the clamp capacitor (CL), the control unit (970) turns on the first switching element (M1H) after the delay-off of the fourth switching element (M2H), turns on the third switching element (M2L) after the turn-on of the first switching element (M1H), and when the third switching element (M2L) is turned on, the third switching element (M2L) can perform a valley switching operation. Accordingly, switching loss can be reduced.

[0405] Figures 16a to 16c illustrate the operation of Mode 5, Mode 5-1, and Mode 6 when the turn-on duty is less than the reference value or when the level of the input voltage (Vin) is greater than the level of the voltage (Vcl) of the clamp capacitor (CL).

[0406] FIG. 16a illustrates a current path by Mode 5 operation of a dc / dc converter according to an embodiment of the present disclosure.

[0407] Referring to the drawing, the control unit (970) can control the second switching element (M1L) to be turned off and the fourth switching element (M2H) to be delayed without being turned off based on Mode 5.

[0408] That is, the control unit (970) can control the second switching element (M1L) to be turned off and the fourth switching element (M2H) to be turned on based on Mode 5.

[0409] Accordingly, a portion of the input current may flow to the output capacitor (Co), the fourth switching element (M2H), the input side of the transformer (Tm), the leakage inductor (Lk), and the parasitic capacitor of the first switching element (M1H).

[0410] Additionally, another portion of the input current may flow to the parasitic capacitor of the second switching element (M1L), and another portion of the input current may flow to the parasitic capacitor of the third switching element (M2L).

[0411] Meanwhile, output current can flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0412] Meanwhile, since the fourth switching element (M2H) is turned on by the Mode 5 operation, the voltage across the third switching element (M2L) can be maintained at the clamp voltage (Vcl).

[0413] And, the voltage across the first switching element (M1H) can be lowered by the first inductor (Lm1) to Vin-Vcl, where the voltage across the second switching element (M1L) and the voltage across the third switching element (M2L) become equal.

[0414] FIG. 16b illustrates the current path by Mode 5-1 operation of the dc / dc converter according to an embodiment of the present disclosure.

[0415] Referring to the drawing, the control unit (970) can control the second switching element (M1L) to be turned off and the fourth switching element (M2H) to be continuously turned on based on Mode 5-1.

[0416] Accordingly, input current can flow to the clamp capacitor (CL), the fourth switching element (M2H), the input side of the transformer (Tm), the leakage inductor (Lk), the parasitic capacitor of the first switching element (M1H), and the parasitic capacitor of the second switching element (M1L).

[0417] Meanwhile, a portion of the output current may flow through one end (ni) of the output side of the transformer (Tm), the first diode (D1), the output capacitor (Co), and the output resistor (Ro), and another portion of the output current may flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0418] Meanwhile, by the Mode 5-1 operation, the voltage at both ends of the first switching element (M1H) can be lowered as in mathematical expression 5 by the leakage inductor (Lk).

[0419] [Equation 5]

[0420]

[0421] Meanwhile, by Mode 5-1 operation, the first switching element (M1H) can perform valley switching.

[0422] Meanwhile, the valley switching timing of the first switching element (M1H) can be determined according to the turn-on duty (D).

[0423] FIG. 16c illustrates the current path by Mode 6 operation of the dc / dc converter according to an embodiment of the present disclosure.

[0424] Referring to the drawing, the control unit (970) can control the second switching element (M1L) to be turned off, the fourth switching element (M2H) to be turned off, and the first switching element (M1H) to be turned on based on Mode 6.

[0425] Accordingly, input current can flow to the first switching element (M1H), the leakage inductor (Lk), the input side of the transformer (Tm), the anti-parallel diode of the fourth switching element (M2H), and the clamp capacitor (CL).

[0426] Meanwhile, a portion of the output current may flow through one end (ni) of the output side of the transformer (Tm), the first diode (D1), the output capacitor (Co), and the output resistor (Ro), and another portion of the output current may flow through the other end (nk) of the output side of the transformer (Tm), the second diode (D2), the output capacitor (Co), and the output resistor (Ro).

[0427] In summary of FIGS. 16A to 17B, when the turn-on duty of the second switching element (M1L) or the turn-on duty of the fourth switching element (M2H) is less than the reference value, the turn-off timing of the fourth switching element (M2H) is delayed from the turn-off timing of the second switching element (M1L), and based on the turn-off of the second switching element (M1L) and the turn-on of the fourth switching element (M2H), current may flow only through the second diode (D2), and then through the first diode (D1) and the second diode (D2), respectively. Accordingly, switching loss can be reduced.

[0428] Meanwhile, based on the turn-on of the first switching element (M1H), current can flow through the first diode (D1) and the second diode (D2), respectively. Accordingly, switching loss can be reduced.

[0429] Meanwhile, the control unit (970) turns on the first switching element (M1H) after the delay-off of the fourth switching element (M2H) when the turn-on duty is less than the reference value or when the level of the input voltage (Vin) is greater than the level of the voltage (Vcl) of the clamp capacitor (CL), and when the delay-off of the fourth switching element (M2H) is performed, the first switching element (M1H) can perform a valley switching operation. Accordingly, switching loss can be reduced.

[0430] Figure 17a describes the operation of Mode 4, Mode 5, Mode 5-1, and Mode 6 when the turn-on duty is less than the reference value or when the level of the input voltage (Vin) is greater than the level of the voltage (Vcl) of the clamp capacitor (CL).

[0431] Referring to the drawing, in Mode 4, the second switching element (M1L) and the fourth switching element (M2H) are turned on, and in Mode 5, only the second switching element (M1L) is turned off and the turn-off of the fourth switching element (M2H) is delayed.

[0432] Next, in Mode 5-1, only the fourth switching element (M2H) is turned on, and in Mode 6, only the first switching element (M1H) is turned on.

[0433] Meanwhile, in Mode 5-1, the first switching element (M1H) can perform valley switching.

[0434] Figure 17b is a drawing referenced in the description of Figure 17a.

[0435] Referring to the drawing, GRca represents a switching control signal of the fourth switching element (M2H), and GRcb represents a switching control signal of the second switching element (M1L).

[0436] When the second switching element (M1L) and the fourth switching element (M2H) are turned on, at time t4b, the second switching element (M1L) is initially turned off, and the turn-off point of the fourth switching element (M2H) is delayed to time t6b.

[0437] Meanwhile, at time t6b, the first switching element (M1H) can be turned on, and at time t7b, the third switching element (M2L) can be turned on.

[0438] GRcc may be a waveform of voltage across the two terminals of the first switching element (M1H), GRcd may be a waveform of voltage across the two terminals of the third switching element (M2L), GRce may be a waveform of voltage across the two terminals of the second switching element (M1L), and GRcf may be a waveform of voltage across the three switching elements (M2L).

[0439] At time t4b, the voltage across the first switching element (M1H) decreases from the input voltage (Vin) and can continue to decrease until time t6b.

[0440] From time t4b to time t7b, the voltage across the third switching element (M2L) can maintain a clamp voltage (Vcl) lower than the input voltage (Vin), and after time t7b, it can decrease.

[0441] Meanwhile, from time t4b to time t6b, the voltage across the two terminals of the second switching element (M1L) may continuously increase. In particular, at time t6b, the voltage across the two terminals of the second switching element (M1L) may be the input voltage (Vin).

[0442] GRcg may represent the waveform of the current (iLm2) flowing in the second inductor (Lm2), and GRch may represent the waveform of the current (iLm1) flowing in the first inductor (Lm1).

[0443] The current (iLm2) flowing in the second inductor (Lm2) sequentially decreases, and then increases again from time t6b.

[0444] The current (iLm1) flowing in the first inductor (Lm1) sequentially decreases, and then increases again from time t5b.

[0445] Figure 17c is a diagram showing switching loss according to turn-on duty.

[0446] Referring to the drawing, the horizontal axis represents the turn-on duty and the vertical axis represents the switching loss.

[0447] Meanwhile, GRma represents the switching loss according to the turn-on duty associated with the present disclosure.

[0448] That is, GRma can correspond to Mode 1 to Mode 6 operations of the dc / dc converter related to the present disclosure of FIGS. 11a to 11f.

[0449] In particular, the switching element can be driven by being divided into a case where the turn-on duty is equal to or greater than the first reference value, a case where it is between the first reference value and the second reference value, and a case where it is less than the second reference value.

[0450] The first criterion at this time may be approximately 0.67, and the second criterion may be approximately 0.5.

[0451] Meanwhile, GRmb represents the switching loss according to the turn-on duty according to the embodiment of the present disclosure.

[0452] That is, GRmb can correspond to Mode 1 to Mode 4, Mode 5, Mode 5-1, and Mode 6 operations when the turn-on duty of the switching element is below a reference value or exceeds a reference value, respectively. The reference value at this time may be 0.5.

[0453] Meanwhile, the control unit (970) in the power conversion device (900) according to the embodiment of the present disclosure can control, based on the GRmb graph, when the turn-on duty is less than or equal to the set value (Pth), to perform operations of Mode 1 to Mode 4, Mode 5, Mode 5-1, and Mode 6, and, based on the GRma graph, to perform operations of Mode 1 to Mode 4, Mode 5, and Mode 6, when the turn-on duty exceeds the set value (Pth). Accordingly, it is possible to operate at maximum efficiency based on the turn-on duty.

[0454] For example, the control unit (970) can control to perform Mode 1 to Mode 4, Mode 5, Mode 5-1, and Mode 6 operations based on the GRmb graph when the turn-on duty is 0 to 0.33, and can control to perform Mode 1 to Mode 4, Mode 5, and Mode 6 operations based on the GRma graph when the turn-on duty is greater than 0.33.

[0455] Meanwhile, the set point (Pth) can be determined based on mathematical expression 6 representing the switching loss based on the GRma graph and mathematical expression 7 representing the switching loss based on the GRmb graph.

[0456] [Equation 6]

[0457]

[0458] [Equation 7]

[0459]

[0460]

[0461] That is, D' corresponding to the set value (Pth) can be calculated by mathematical expression 8.

[0462] [Equation 8]

[0463]

[0464]

[0465] For example, the setpoint (Pth) calculated by Equation 8 may be 0.33.

[0466] Meanwhile, the control unit (970) in the power conversion device (900) according to another embodiment of the present disclosure delays the turn-off timing of the fourth switching element (M2H) longer than the turn-off timing of the second switching element (M1L) when the second switching element (M1L) and the fourth switching element (M2H) are turned on, and when the turn-on duty of the second switching element (M1L) or the turn-on duty of the fourth switching element (M2H) is less than a reference value, turns on the first switching element (M1H) after the delay-off of the fourth switching element (M2H), and performs a valley switching operation when the delay-off of the fourth switching element (M2H) is performed. Accordingly, switching loss can be reduced.

[0467] Meanwhile, the control unit (970) in the power conversion device (900) according to another embodiment of the present disclosure delays the turn-off timing of the fourth switching element (M2H) longer than the turn-off timing of the second switching element (M1L) when the second switching element (M1L) and the fourth switching element (M2H) are turned on, and if the turn-on duty of the second switching element (M1L) or the turn-on duty of the fourth switching element (M2H) is equal to or greater than a reference value, turns on the first switching element (M1H) after the delay-off of the fourth switching element (M2H), and when the first switching element (M1H) is turned on, the first switching element (M1H) performs a valley switching operation, and turns on the third switching element (M2L) after the first switching element (M1H) is turned on. Accordingly, switching loss can be reduced.

[0468] Although the preferred embodiments of the present disclosure have been illustrated and described above, the present disclosure is not limited to the specific embodiments described above, and various modifications may be made by a person skilled in the art to which the present invention pertains without departing from the gist of the present disclosure as claimed in the claims, and such modifications should not be understood individually from the technical idea or prospect of the present disclosure.

Claims

1. Transformer; A first switching element and a second switching element are arranged on the input side of the transformer and are connected in series with each other; An inductor connected to one end of the input side of the above transformer; A third switching element and a fourth switching element each connected to the other end of the input side of the transformer; A clamp capacitor connected between the fourth switching element and the third switching element; A power conversion device in which, when the second switching element and the fourth switching element are turned on, the turn-off point of the fourth switching element is delayed compared to the turn-off point of the second switching element.

2. In paragraph 1, An input voltage detection unit that detects an input voltage input to the first switching element; A power conversion device further comprising a control unit that controls the first to fourth switching elements based on the detected input voltage.

3. In paragraph 2, The above control unit, A power conversion device that controls the delay period of the delay so that the higher the level of the input voltage, the longer the delay period.

4. In paragraph 2, The above control unit, A power conversion device that varies the turn-on duty of the second switching element or the turn-on duty of the fourth switching element based on the level of the input voltage.

5. In paragraph 2, The above control unit, A power conversion device that controls the turn-on duty of the second switching element or the turn-on duty of the fourth switching element to increase as the level of the input voltage decreases.

6. In paragraph 2, The above control unit, A power conversion device that turns on the first switching element after the delay-off of the fourth switching element.

7. In paragraph 2, The above control unit, A power conversion device that turns on the first switching element after the delay-off of the fourth switching element, and turns on the third switching element after the turn-on of the first switching element.

8. In paragraph 2, The above control unit, When the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is less than a reference value, after the delay-off of the fourth switching element, the first switching element is turned on, A power conversion device in which the first switching element performs a valley switching operation when the fourth switching element is delayed off.

9. In paragraph 2, The above control unit, When the turn-on duty of the first switching element or the turn-on duty of the third switching element is greater than or equal to a reference value, after the delay-off of the fourth switching element, the first switching element is turned on, and after the turn-on of the first switching element, the third switching element is turned on. A power conversion device in which, when the third switching element is turned on, the third switching element performs a valley switching operation.

10. In paragraph 2, The above control unit, When the level of the input voltage is greater than the level of the voltage of the clamp capacitor, after the delay-off of the fourth switching element, the first switching element is turned on, A power conversion device in which the first switching element performs a valley switching operation when the fourth switching element is delayed off.

11. In paragraph 2, The above control unit, When the level of the input voltage is lower than or equal to the voltage level of the clamp capacitor, after the delay-off of the fourth switching element, the first switching element is turned on, and after the turn-on of the first switching element, the third switching element is turned on. A power conversion device in which, when the third switching element is turned on, the third switching element performs a valley switching operation.

12. In paragraph 1, A power conversion device wherein, at the end of the delay, the voltage across the third switching element is equal to the voltage of the clamp capacitor.

13. In paragraph 1, A power conversion device in which the inductance of the above inductor is greater than the inductance of the leakage inductor on the input side of the transformer.

14. In paragraph 1, A first diode connected to one end of the output side of the above transformer; A power conversion device further comprising a second diode connected to one end of the output side of the transformer.

15. In paragraph 14, During the first period, based on the turn-on of the first switching element and the third switching element, current flows through the first diode, A power conversion device in which, after the first period, current flows through the second diode based on the turn-on of the second switching element and the fourth switching element.

16. In paragraph 14, If the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is less than the reference value, A power conversion device in which the turn-off timing of the fourth switching element is delayed from the turn-off timing of the second switching element, and based on the turn-off of the second switching element and the turn-on of the fourth switching element, current flows only through the second diode, and then current flows through the first diode and the second diode, respectively.

17. In paragraph 14, If the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is greater than or equal to the reference value, A power conversion device in which the turn-off timing of the fourth switching element is delayed from the turn-off timing of the second switching element, and current flows through the second diode based on the turn-off of the second switching element and the turn-on of the fourth switching element.

18. Transformers; A first switching element and a second switching element are arranged on the input side of the transformer and are connected in series with each other; An inductor connected to one end of the input side of the above transformer; A third switching element and a fourth switching element each connected to the other end of the input side of the transformer; A clamp capacitor connected between the fourth switching element and the third switching element; It comprises a control unit that controls the first to fourth switching elements; The above control unit, In a state where the second switching element and the fourth switching element are turned on, the turn-off point of the fourth switching element is delayed compared to the turn-off point of the second switching element, When the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is less than a reference value, after the delay-off of the fourth switching element, the first switching element is turned on, A power conversion device in which the first switching element performs a valley switching operation when the fourth switching element is delayed off.

19. Transformers; A first switching element and a second switching element are arranged on the input side of the transformer and are connected in series with each other; An inductor connected to one end of the input side of the above transformer; A third switching element and a fourth switching element each connected to the other end of the input side of the transformer; A clamp capacitor connected between the fourth switching element and the third switching element; It comprises a control unit that controls the first to fourth switching elements; The above control unit, In a state where the second switching element and the fourth switching element are turned on, the turn-off point of the fourth switching element is delayed compared to the turn-off point of the second switching element, A power conversion device that turns on the first switching element after the delay-off of the fourth switching element when the turn-on duty of the second switching element or the turn-on duty of the fourth switching element is greater than or equal to a reference value, and when the first switching element is turned on, the first switching element performs a valley switching operation, and turns on the third switching element after the turn-on of the first switching element.

Images