Relay device and battery charging device having the same

Abstract

The invention relates to a relay device and a battery charging device having the same. A relay device according to an embodiment of the present disclosure includes: a current limiter that limits a current input to an AC power source; the primary side of the relay is connected between the first end and the second end of the current limiter; a first power supply unit connected between a third terminal, which is a secondary side of the relay, and a ground terminal, and supplying a first power source; a first switching element connected between a fourth terminal, which is a secondary side of the relay, and a ground terminal; and a second power supply section and a second switching element connected in series between the fourth terminal and the ground terminal; the second power supply unit supplies a second power lower than the first power. Thus, heat generation of the relay can be reduced.

Description

Technical Field

[0001] The present disclosure relates to a relay device and a battery charging device having the relay device. More specifically, the present disclosure relates to a relay device capable of reducing heat generation of a relay and a battery charging device having the relay device. Background Art

[0002] Electric vehicles powered by electricity or hybrid vehicles combining an internal combustion engine use motors and batteries to generate output.

[0003] In order to charge a DC power source from an AC power source, a charging device is required.

[0004] On the other hand, when an AC power source is instantaneously supplied, an inrush current occurs. Due to the inrush current, the possibility of burnout of internal circuit elements increases, and therefore, an inrush current prevention circuit for preventing this phenomenon is required.

[0005] On the other hand, when a relay is used to implement an inrush current prevention circuit, there is a problem of increased heat generation in the relay. Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] An object of the present disclosure is to provide a relay device capable of reducing heat generation of a relay and a battery charging device having the relay device.

[0008] Another object of the present disclosure is to provide a relay device capable of preventing an inrush current during battery charging and a battery charging device having the relay device.

[0009] Means for Solving the Problems

[0010] To achieve the above object, a relay device and a battery charging device having the relay device according to an embodiment of the present disclosure include: a current limiter that limits the current of an input AC power source; a relay, the primary side of which is connected between both ends, i.e., a first end and a second end, of the current limiter; a first power supply unit that is connected between a third end, which is the secondary side of the relay, and a ground terminal and supplies a first power supply; a first switching element that is connected between a fourth end, which is the secondary side of the relay, and the ground terminal; and a second power supply unit and a second switching element that are connected in series between the fourth end and the ground terminal, and the second power supply unit supplies a second power supply lower than the first power supply.

[0011] On the other hand, when the first switching element is turned on and the second switching element is turned off, the first power supply is supplied to the relay. When the first switching element is turned off and the second switching element is turned on, the difference between the first power supply and the second power supply, i.e., the third power supply, is supplied to the relay.

[0012] On the other hand, when the first switching element is turned on and the second switching element is turned off, the first power supply is supplied to the relay. When the first switching element is turned on and the second switching element is turned on, the first power supply is supplied to the relay. When the first switching element is turned off and the second switching element is turned on, the difference between the first power supply and the second power supply, i.e., the third power supply, is supplied to the relay.

[0013] On the other hand, based on the operation of the first switching element or the second switching element, power supplies of multiple levels can be sequentially supplied to the coil in the relay.

[0014] On the other hand, during the first time period, the first current of the input AC power supply flows through the current limiter. During the second time period after the first time period, the second current of the input AC power supply flows through the relay.

[0015] On the other hand, the second current level can be greater than the first current level.

[0016] On the other hand, during the second time period, based on the operation of the first switching element or the second switching element, power supplies of multiple levels can be sequentially supplied to the coil in the relay.

[0017] The relay device according to another embodiment of the present disclosure and the battery charging device having the relay device include: a current limiter that limits the current of the input AC power supply; a relay, the primary side of the relay being connected between the two ends, i.e., the first end and the second end, of the current limiter; a power supply unit connected between the third end, which is the secondary side of the relay, and the ground terminal; a switching element connected between the fourth end, which is the secondary side of the relay, and the ground terminal; the power supply unit supplies the first power supply and then supplies the second power supply that is lower than the first power supply.

[0018] On the other hand, when the switching element is turned on, the first power supply is supplied to the relay, and then the second power supply that is lower than the first power supply is supplied to the relay.

[0019] On the other hand, during the first time period, the first current of the input AC power supply flows through the current limiter. During the second time period after the first time period, the second current of the input AC power supply flows through the relay.

[0020] On the other hand, the second current level can be greater than the first current level.

[0021] On the other hand, during the second period, based on the operation of the switching element, power supplies of a plurality of levels can be sequentially supplied to the coil in the relay.

[0022] The battery charging device according to an embodiment of the present disclosure may further include: a rectifying unit that rectifies an AC power supply from the relay device; a converter that converts the power supply from the rectifying unit into a DC power supply; and a DC link capacitor disposed at an output end of the converter.

[0023] On the other hand, the battery charging device according to an embodiment of the present disclosure may further include a DC / DC converter that converts the level of the DC voltage of the DC link capacitor.

[0024] Effects of the Invention

[0025] The relay device according to an embodiment of the present disclosure and a battery charging device having the relay device include: a current limiter that limits the current of an input AC power supply; a relay whose primary side is connected between two ends, i.e., a first end and a second end, of the current limiter; a first power supply unit that is connected between a third end, which is a secondary side of the relay, and a ground end and supplies a first power supply; a first switching element that is connected between a fourth end, which is a secondary side of the relay, and the ground end; a second power supply unit and a second switching element that are connected in series between the fourth end and the ground end; and the second power supply unit supplies a second power supply lower than the first power supply. Thereby, heat generation of the relay can be reduced. Further, inrush current can be prevented during battery charging.

[0026] On the other hand, when the first switching element is turned on and the second switching element is turned off, the first power supply is supplied to the relay, and when the first switching element is turned off and the second switching element is turned on, a third power supply, which is the difference between the first power supply and the second power supply, is supplied to the relay. In this way, as power supplies of different levels are sequentially supplied to the relay, heat generation of the relay can be reduced.

[0027] On the other hand, when the first switching element is turned on and the second switching element is turned off, the first power supply is supplied to the relay, when the first switching element is turned on and the second switching element is turned on, the first power supply is supplied to the relay, and when the first switching element is turned off and the second switching element is turned on, a third power supply, which is the difference between the first power supply and the second power supply, is supplied to the relay. In this way, as power supplies of different levels are sequentially supplied to the relay, heat generation of the relay can be reduced.

[0028] On the other hand, based on the operation of the first switching element or the second switching element, power supplies of a plurality of levels can be sequentially supplied to the coil in the relay. In this way, as power supplies of different levels are sequentially supplied to the relay, heat generation of the relay can be reduced.

[0029] On the other hand, during a first period, a first current of an input AC power supply can flow through a current limiter, and during a second period after the first period, a second current of the input AC power supply can flow through a relay. Thus, surge current can be prevented during battery charging.

[0030] On the other hand, the second current level can be greater than the first current level. Thus, surge current can be prevented during battery charging.

[0031] On the other hand, during the second period, power supplies of a plurality of levels can be sequentially supplied to a coil in the relay based on the operation of a first switching element or a second switching element. In this way, as different-level power supplies are sequentially supplied to the relay, heat generation of the relay can be reduced.

[0032] A relay device according to another embodiment of the present disclosure and a battery charging device having the relay device include: a current limiter that limits the current of an input AC power supply; a relay whose primary side is connected between a first end and a second end at both ends of the current limiter; a power supply unit connected between a third end, which is the secondary side of the relay, and a ground terminal; a switching element connected between a fourth end, which is the secondary side of the relay, and the ground terminal; the power supply unit supplies a first power supply and then supplies a second power supply lower than the first power supply. Thus, heat generation of the relay can be reduced. Furthermore, surge current can be prevented during battery charging.

[0033] On the other hand, when the switching element is turned on, the first power supply can be supplied to the relay, and then the second power supply lower than the first power supply can be supplied to the relay. In this way, as different-level power supplies are sequentially supplied to the relay, heat generation of the relay can be reduced.

[0034] On the other hand, during a first period, a first current of an input AC power supply can flow through a current limiter, and during a second period after the first period, a second current of the input AC power supply can flow through a relay. Thus, surge current can be prevented during battery charging.

[0035] On the other hand, the second current level can be greater than the first current level. Thus, surge current can be prevented during battery charging.

[0036] On the other hand, during the second period, power supplies of a plurality of levels can be sequentially supplied to a coil in the relay based on the operation of the switching element. In this way, as different-level power supplies are sequentially supplied to the relay, heat generation of the relay can be reduced.

[0037] The battery charging device according to an embodiment of the present disclosure may further include: a rectifying unit that rectifies an AC power supply from a relay device; a converter that converts the power supply from the rectifying unit into a DC power supply; and a DC link capacitor disposed at an output end of the converter. Thereby, heat generation of the relay can be reduced. Furthermore, inrush current can be prevented during battery charging.

[0038] On the other hand, the battery charging device according to an embodiment of the present disclosure may further include a DC / DC converter that converts the level of the DC voltage of the DC link capacitor. Thereby, heat generation of the relay can be reduced. Furthermore, inrush current can be prevented during battery charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic diagram showing a vehicle body according to an embodiment of the present disclosure.

[0040] Figure 2 is an example of a motor drive system according to an embodiment of the present disclosure.

[0041] Figure 3 ILLUSTRATION Figure 2 is an example of an internal block diagram of the illustrated motor drive device.

[0042] Figure 4 is Figure 3 an example of an internal circuit diagram of the motor drive device.

[0043] Figure 5 is Figure 4 an example of an internal block diagram of the inverter control unit.

[0044] Figure 6 is a block diagram showing a battery charging device according to an embodiment of the present disclosure.

[0045] Figure 7a is an example of a circuit diagram of a relay device related to the present disclosure.

[0046] Figure 7b is Figure 7a a figure referred to in the description of

[0047] Figure 8 is an example of a circuit diagram of a relay device according to an embodiment of the present disclosure.

[0048] Figures 9a to 9b is Figure 8 a figure referred to in the description of

[0049] Figure 10 is an example of a circuit diagram of a relay device according to another embodiment of the present disclosure.

[0050] Figures 11a to 11b is Figure 10 a figure referred to in the description of Detailed Implementation Manner

[0051] Hereinafter, the present disclosure will be described in more detail with reference to the accompanying drawings.

[0052] In the following description, the suffixes "module" and "section" of the components used are only given for the convenience of writing this specification, and they do not give any particularly important meaning or function by themselves. Therefore, the "module" and "section" can also be used interchangeably with each other.

[0053] Figure 1 It is a schematic diagram showing the body of a vehicle according to an embodiment of the present disclosure.

[0054] Referring to the accompanying drawings, a vehicle 100 according to an embodiment of the present disclosure may include: a battery 205 that supplies power, a motor drive device 200 that receives power from the battery 205, a motor 250 that is driven to rotate by the motor drive device 200, front wheels 150 and rear wheels 155 that are rotated by the motor 250, a front wheel suspension device 160 and a rear wheel suspension device 165 that block the transmission of road surface vibrations to the body, and an inclination angle detection unit 190 that detects the inclination angle of the body. On the other hand, a drive gear (not shown) that converts the rotational speed of the motor 250 based on a gear ratio may be additionally provided.

[0055] The battery 205 supplies power to the motor drive device 200. In particular, a DC power supply is supplied to the capacitor C in the motor drive device 200.

[0056] Such a battery 205 may be formed by a collection of a plurality of unit cells. The plurality of unit cells can be managed by a Battery Management System (BMS) in order to maintain a constant voltage, and a constant voltage can be issued through the battery management system.

[0057] For example, the battery management system can detect the voltage Vbat of the battery 205, transmit it to an electronic control unit (not shown) or the inverter control unit 430 in the motor drive device 200, and when the battery voltage Vbat drops below the lower limit value, the DC power stored in the capacitor C in the motor drive device 200 can be supplied to the battery. In addition, when the battery voltage Vbat rises above the upper limit value, the DC power can also be supplied to the capacitor C in the motor drive device 200.

[0058] The battery 205 is preferably composed of a secondary battery that can be charged and discharged, but is not limited thereto.

[0059] The motor drive device 200 receives DC power from the battery 205 through the power input cable 120. The motor drive device 200 converts the DC power received from the battery 205 into AC power and supplies it to the motor 250. The converted AC power is preferably three-phase AC power. The motor drive device 200 supplies three-phase AC power to the motor 250 through the three-phase output cable 125 that the motor drive device 200 has.

[0060] Figure 1 Although the motor drive device 200 of is shown with a three-phase output cable 125 composed of three cables, it may have three cables within a single cable.

[0061] On the other hand, the motor drive device 200 of the embodiments of the present disclosure will be described with reference to Figure 3 described later.

[0062] The motor 250 includes a stator 131 that does not rotate and is fixed and a rotor 135 that rotates. The motor 250 has an input cable 140 and is applied with AC power supplied from the motor drive device 200. The motor 250 may be, for example, a three-phase motor. When three-phase AC power with variable voltage / variable frequency is applied to the coils of the stator of each phase, the rotational speed of the rotor is variable based on the applied frequency.

[0063] The motor 250 may be in various forms such as an induction motor, a brushless DC motor (BLDC motor), a reluctance motor, etc.

[0064] On the other hand, one side of the motor 250 may have a drive gear (not shown). The drive gear converts the rotational energy of the motor 250 based on the gear ratio. The rotational energy output from the drive gear is transmitted to the front wheel 150 and / or the rear wheel 155 to move the vehicle 100.

[0065] The front wheel suspension device 160 and the rear wheel suspension device 165 support the front wheel 150 and the rear wheel 155 relative to the vehicle body, respectively. The up-and-down directions of the front wheel suspension device 160 and the rear wheel suspension device 165 are supported by springs or damping mechanisms so that the vibrations of the road surface are not transmitted to the vehicle body.

[0066] The front wheel 150 may also have a steering device (not shown). The steering device is a device that adjusts the direction of the front wheel 150 so that the vehicle 100 travels in the direction expected by the driver.

[0067] On the other hand, although not shown, the vehicle 100 may further include an electronic control unit (Electronic Controller) for controlling the electronic devices of the entire vehicle. The electronic control unit (not shown) controls each device to be able to perform actions, displays, etc. In addition, it may also control the above-mentioned battery management system.

[0068] In addition, the control unit ( Figure 2 170) may generate a driving command value corresponding to various driving modes (such as a driving mode, a reverse mode, a neutral mode, and a parking mode, etc.) based on detection signals from an inclination angle detection unit (not shown) for detecting the inclination angle of the vehicle 100, a speed detection unit (not shown) for detecting the speed of the vehicle 100, a braking detection unit (not shown) based on the operation of the brake pedal, an acceleration detection unit (not shown) based on the operation of the accelerator pedal, etc. The driving command value at this time may be, for example, a torque command value or a torque command value.

[0069] On the other hand, the vehicle 100 according to an embodiment of the present disclosure may not only be a pure electric vehicle including a battery and a motor, but also a concept of a hybrid electric vehicle using an engine and a battery and a motor.

[0070] At this time, the hybrid electric vehicle may also have a switching mechanism and a transmission capable of selecting at least any one of the battery and the engine.

[0071] On the other hand, the hybrid electric vehicle may be classified into a series type that converts mechanical energy output from the engine into electrical energy to drive the motor, a parallel type that simultaneously uses mechanical energy output from the engine and electrical energy from the battery, and a series-parallel type that combines them.

[0072] Figure 2 is an example of a motor drive system according to an embodiment of the present disclosure.

[0073] Referring to the drawings, a motor drive system according to an embodiment of the present disclosure may include a vehicle 100 and a server 500.

[0074] Among them, the server 500 may correspond to a server operated by a manufacturer of the motor drive device 200 or the vehicle 100, or a mobile terminal of a driver of the motor drive device 200 or the vehicle 100, etc.

[0075] On the other hand, the vehicle 100 may include an input unit 120, a communication unit 130, a memory 140, a control unit 170, and a motor drive device 200.

[0076] The input unit 120 has operation buttons, keys, etc., and may output input signals for turning on / off the power of the vehicle 100, action setting, etc.

[0077] The communication unit 130 can exchange data with peripheral devices such as the server 500 either wired or wirelessly, or exchange data with remote servers etc. wirelessly. For example, it can perform mobile communications such as 4G or 5G, infrared (IR) communication, radio frequency (RF) communication, Bluetooth communication, ZigBee communication, WiFi communication, etc.

[0078] On the other hand, the memory 140 of the vehicle 100 can store data required for the operation of the vehicle 100. For example, it can store data such as the operation time and operation mode during the operation of the motor drive device 200.

[0079] In addition, the memory 140 of the vehicle 100 can store management data including the power consumption information of the vehicle, recommended driving information, current driving information, and management information.

[0080] In addition, the memory 140 of the vehicle 100 can store diagnostic data including the operation information, driving information, and error information of the vehicle.

[0081] 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 drive device 200, etc.

[0082] The motor drive device 200, as a drive unit for driving the motor 250, can also be named the motor drive part.

[0083] On the other hand, the motor drive device 200 has a plurality of inverter switching elements and can include: an inverter 420 that outputs an AC power supply to the motor 250; an output current detection unit E that detects the output current io flowing through the motor 250; and an inverter control unit 430 that outputs a switching control signal to the inverter 420 based on the current information id, iq of the output current io detected by the output current detection unit E and the torque command value T*.

[0084] On the other hand, the current information id, iq of the output current io and the torque command value T* can be transmitted to the external server 500, and the current command values i*d, i*q can also be received from the server 500. And based on the current command value received from the communication unit 130, the inverter control unit 430 can also output a switching control signal to the inverter 420.

[0085] Thus, the motor 250 can be driven based on the current command value corresponding to the maximum torque calculated in real time in the server 500. Therefore, the maximum torque drive of the motor 250 can be achieved.

[0086] On the other hand, the communication unit 130 within the motor drive device 200 can transmit the current information id, iq, the torque command value T*, and voltage information related to the detected dc terminal voltage Vdc to the server 500. Thereby, maximum torque drive of the motor 250 under various conditions can be achieved.

[0087] On the other hand, refer to Figure 3 Describe the detailed operation of the motor drive device 200.

[0088] Figure 3 Illustrate Figure 2 An example of the internal block diagram of the illustrated motor drive device.

[0089] Referring to the drawings, the motor drive device 200 of an embodiment of the present disclosure, as a drive device for driving the motor 250, has a plurality of inverter switching elements Sa to Sc, S'a to S'c, and may include an inverter 420 that outputs an AC power supply to the motor 250 and an inverter control unit 430 that controls the inverter 420. In addition, it may include a memory 270 that provides various stored data to the inverter control unit 430.

[0090] On the other hand, the motor drive device 200 of an embodiment of the present disclosure may also have a capacitor C that stores the dc terminal voltage Vdc at the input terminal of the inverter 420, a dc terminal voltage detection unit B that detects the dc terminal voltage Vdc, an output current detection unit E that detects the output current flowing through the motor 250, and a position detection sensor 105.

[0091] The motor 250 of an embodiment of the present disclosure may be a three-phase motor driven by the inverter 420.

[0092] On the other hand, the inverter control unit 430 may output a switching control signal Sic to the inverter 420 based on the current command values i*d, i*q corresponding to the calculated maximum torque. Therefore, maximum torque drive of the motor 250 can be achieved.

[0093] The inverter control unit 430 of an embodiment of the present disclosure calculates the current information id, iq and the torque command value T* in real time, calculates the current command values i*d, i*q based on the torque command value T*, and drives the motor 250 using the current command values i*d, i*q. Thereby, the correctness for efficient drive is improved.

[0094] On the other hand, the motor drive device 200 may also include a capacitor C that stores the dc terminal voltage Vdc at the input terminal of the inverter 420 and a dc terminal voltage detection unit B that detects the dc terminal voltage Vdc.

[0095] The inverter control unit 430 calculates current command values i*d and i*q based on the current information id, iq, the torque command value T*, and the detected dc-link voltage Vdc, and drives the motor 250 using the current command values i*d and i*q. Thereby, the accuracy for efficient driving is improved.

[0096] Figure 4 Yes Figure 3 An example of the internal circuit diagram of the motor drive device.

[0097] Referring to the accompanying drawings, the motor drive 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-link voltage detection unit Vdc, and a position detection sensor 105.

[0098] On the other hand, since the motor drive device 200 converts electric power to drive the motor, it may also be named a power conversion device.

[0099] The dc-link capacitor C stores the power supply input to the dc-link (a-b terminal). In the drawings, although one element is illustrated as the dc-link capacitor C, a plurality of elements may also be provided to ensure element stability.

[0100] On the other hand, the input power supply supplied to the dc-link capacitor C may be the power stored in the battery 205 or the power level-converted in a converter (not shown).

[0101] On the other hand, since a DC power supply is stored across the dc-link capacitor C, it may also be named the dc-link or the dc-link terminal.

[0102] The dc-link voltage detection unit B may detect the dc-link voltage Vdc across the dc-link capacitor C. To this end, the dc-link voltage detection unit B may include a resistance element, an amplifier, etc. The detected dc-link voltage Vdc may be input to the inverter control unit 430 as a discrete signal in a pulse form.

[0103] The inverter 420 has a plurality of inverter switch elements Sa to Sc, S'a to S'c, and can convert the DC power supply Vdc into a three-phase AC power supply Va, Vb, Vc of a specified frequency by the on / off operation of the switch elements Sa to Sc, S'a to S'c, and output it to the three-phase synchronous motor 250.

[0104] In the case of the inverter 420, the upper-arm switching elements Sa, Sb, and Sc and the lower-arm switching elements S'a, S'b, and S'c, which are connected in series with each other, form a pair, and a total of three pairs of upper and lower-arm switching elements are connected in parallel with each other as Sa&S'a, Sb&S'b, and Sc&S'c. Diodes are anti-parallel connected in each of the switching elements Sa, S'a, Sb, S'b, Sc, and S'c.

[0105] A plurality of switching elements in 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. Thereby, a three-phase AC power supply having a specified frequency is output to the three-phase synchronous motor 250.

[0106] The inverter control unit 430 can control the switching operation of the inverter 420 based on a sensorless method.

[0107] For this purpose, the inverter control unit 430 can receive the output current io detected by the output current detection unit E.

[0108] In order to control the switching operation of the inverter 420, the inverter control unit 430 can output the inverter switching control signal Sic to each gate terminal of the inverter 420. Thereby, the inverter switching control signal Sic can also be named as a gate drive signal.

[0109] On the other hand, the inverter switching control signal Sic is a switching control signal of a pulse width modulation (PWM) method, and is generated and output based on the output current io detected by the output current detection unit E.

[0110] 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 through the motor 250 can be detected.

[0111] The output current detection unit E can detect all the output currents ia, ib, and ic of each phase, or can also detect the output currents of two phases by using three-phase balance.

[0112] The output current detection unit E can be located between the inverter 420 and the motor 250, and a current transformer (CT), a shunt resistor, etc. can be used for current detection.

[0113] The detected output current io can be applied to the inverter control unit 430 as a discrete signal in a pulse form, and the switching control signal Sic is generated based on the detected output current io.

[0114] 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.

[0115] On the other hand, the three-phase motor 250 has a stator and a rotor, and an alternating current power supply of each phase at a specified frequency is applied to the coils of the stator of each phase a, b, and c, causing the rotor to rotate.

[0116] Such a motor 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 them, SMPMSM and IPMSM are Permanent Magnet Synchronous Motors (PMSM) that apply permanent magnets, and the characteristic of Synrm is that it has no permanent magnets.

[0117] On the other hand, the motor 250 of the embodiments of the present disclosure will be mainly described as an Interior Permanent Magnet Synchronous Motor (IPMSM).

[0118] Figure 5 is Figure 4 An example of the internal block diagram of the inverter control unit.

[0119] Referring to the drawings, Figure 5 the inverter control unit 430 of can receive the detected output current io from the output current detection unit 320 and the rotor position information θ of the motor 250 from the position detection sensor 105.

[0120] 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.

[0121] For this purpose, the position detection sensor 105 may include an encoder or a resolver, etc.

[0122] The coordinate system and coordinate axes used in the following description are defined herein.

[0123] The αβ coordinate system is a two-dimensional fixed coordinate system with the fixed axes being the α axis and the β axis. The α axis and the β axis are orthogonal to each other, and the β axis is 90° electrical angle ahead of the α axis.

[0124] The dq coordinate system is a two-dimensional rotating coordinate system with the rotating axes being the d-axis and the q-axis. In a rotating coordinate system that rotates at the same speed as the rotational speed of the magnetic flux generated by the permanent magnet of the motor 250, the axis along the direction of the magnetic flux generated by the permanent magnet is the d-axis, and the axis that is 90° electrical angle ahead in phase of the d-axis is the q-axis.

[0125] Referring to Figure 5 , the inverter control unit 430 may include a speed calculation unit 320, a coordinate transformation unit 310, a torque calculation unit 325, a current command generation unit 330, a voltage command generation unit 340, a coordinate transformation unit 350, and a switching control signal output unit 360.

[0126] The coordinate transformation unit 310 within the inverter control unit 430 receives the three-phase output currents ia, ib, and ic detected by the output current detector E, and converts them into two-phase currents iα and iβ in the stationary coordinate system.

[0127] On the other hand, the coordinate transformation unit 310 may convert the two-phase currents iα and iβ in the stationary coordinate system into two-phase currents id and iq in the rotating coordinate system.

[0128] The speed calculation unit 320 within the inverter control unit 430 estimates the rotor position of the motor 250 based on the two-phase currents iα and iβ in the stationary coordinate system that are transformed by the coordinate transformation unit 310. Additionally, the calculated speed may be output based on the estimated rotor position.

[0129] The torque calculation unit 325 within the inverter control unit 430 may calculate the current torque T based on the calculated speed.

[0130] The current command generation unit 330 within the inverter control unit 430 generates current command values i*d and i*q based on the calculated current torque T and the torque command value T*.

[0131] For example, the current command generation unit 330 may perform PI control in the PI controller 335 based on the calculated current torque T and the torque command value T*, and generate current command values i*d and i*q. On the other hand, the value of the d-axis current command value i*d may also be set to 0.

[0132] On the other hand, the current command generation unit 330 may also have a limiter (not shown), which limits its level so that the current command values i*d and i*q do not exceed the allowable range.

[0133] Next, the voltage command generation unit 340 generates d-axis and q-axis voltage command values V*d and V*q based on the d-axis and q-axis currents id and iq that are coordinate-transformed into the two-phase rotating coordinate system in the coordinate transformation unit, and the current command values i*d and i*q in the current command generation unit 330, etc.

[0134] For example, the voltage command generation unit 340 performs PI control in the PI controller 344 based on the difference between the q-axis current iq and the q-axis current command value i*q, and can generate the q-axis voltage command value V*q. In addition, the voltage command generation unit 340 can perform PI control in the PI controller 348 based on the difference between the d-axis current id and the d-axis current command value i*d, and generate the d-axis voltage command value V*d. On the other hand, the value of the d-axis voltage command value V*d corresponds to the case where the value of the d-axis current command value i*d is set to 0, and can also be set to 0.

[0135] On the other hand, the voltage command generation unit 340 may also have a limiter (not shown), which limits its level so that the d-axis and q-axis voltage command values V*d and V*q do not exceed the allowable range.

[0136] On the other hand, the generated d-axis and q-axis voltage command values V*d and V*q are input to the axis conversion unit 350.

[0137] The axis conversion unit 350 receives the position calculated in the speed calculation unit 320 and the d-axis and q-axis voltage command values V*d and V*q to perform axis conversion.

[0138] First, the axis conversion unit 350 performs a conversion from a two-phase rotating coordinate system to a two-phase stationary coordinate system. At this time, the position calculated in the speed calculation unit 320 can be used.

[0139] And, the axis conversion unit 350 performs a conversion from a two-phase stationary coordinate system to a three-phase stationary coordinate system. Through such a conversion, the axis conversion unit 350 outputs the three-phase output voltage command values V*a, V*b, and V*c.

[0140] The switch control signal output unit 360 can generate and output a switch control signal Sic based on the pulse width modulation (PWM) method based on the three-phase output voltage command values V*a, V*b, and V*c.

[0141] The output inverter switch control signal Sic can be converted into a gate drive signal in a gate drive unit (not shown) and input to the gates of the respective switch elements in the inverter 420. Thereby, the respective switch elements Sa, S'a, Sb, S'b, Sc, and S'c in the inverter 420 perform a switching operation.

[0142] Figure 6 It is a block diagram showing a battery charging device according to an embodiment of the present disclosure.

[0143] Referring to the accompanying drawings, the battery charging device 610 may include a filter 620 that removes noise from the input AC power supply (Vac) 201, a relay device 630 that prevents inrush current of the AC power supply 201 from the filter 620, a rectifying unit 640 that rectifies the AC power supply 201 from the relay device 630, and a converter 650 that converts the power from the rectifying unit 640 into a DC power supply.

[0144] The filter 620 may have an inductor or a capacitor and may be implemented in various forms such as an LLC filter, an LCC filter, etc.

[0145] In order to prevent inrush current based on the input AC power supply Vac 201, the relay device 630 may output a first current during a first period and output a second current larger than the first current during a second period after the first period.

[0146] Thus, inrush current can be prevented during the first period.

[0147] On the other hand, the battery charging device 610 may further include a DC link capacitor 655 disposed at the output end of the converter 650, a DC / DC converter 670 that converts the level of the DC voltage of the DC link capacitor 655, and a filter 680 that removes noise from the output voltage of the DC / DC converter 670.

[0148] Thus, the battery charging device 610 can convert an AC voltage into a DC voltage and store the DC voltage in the battery 205.

[0149] On the other hand, the filter 620, the relay device 630, the rectifying unit 640, the converter 650, the DC link capacitor 655, the DC / DC converter 670, and the filter 680 in the battery charging device 610 may be disposed within a single circuit board. Thus, the battery charging device 610 may also be named an on-board charger.

[0150] On the other hand, the filter 620, the relay device 630, the rectifying unit 640, the converter 650, and the DC link capacitor 655 in the battery charging device 610 may be connected to a first ground. The first ground at this time may correspond to the ground of the input AC power supply Vac 201.

[0151] On the other hand, the DC / DC converter 670 and the filter 680 in the battery charging device 610 may be connected to a second ground. The second ground at this time may correspond to the ground of the battery 205.

[0152] That is, the DC / DC converter 670 and the filter 680 in the battery charging device 610 can be set to be grounded and insulated separately from other internal units.

[0153] On the other hand, the output terminal of the converter 650 can correspond to Figure 4 the node (node) a - node (node) b, whereby the DC link capacitor 655 can correspond to Figure 4 the capacitor C in the motor drive device 200 of

[0154] For example, in the charging mode when the vehicle is stopped, the battery charging device 610 can charge the battery 205 with a DC voltage based on the power or energy movement in the direction of the filter 620, the relay device 630, the rectifying unit 640, the converter 650, the DC link capacitor 655, the DC / DC converter 670, the filter 680, and the battery 205.

[0155] On the other hand, during vehicle driving, the filter 620, the relay device 630, the rectifying unit 640, and the converter 650 in the battery charging device 610 may not operate.

[0156] On the other hand, in the discharging mode when the vehicle is driving, the filter 620, the relay device 630, the rectifying unit 640, and the converter 650 do not operate. Based on the power or energy movement in the direction of the battery 205, the filter 680, the DC / DC converter 670, and the DC link capacitor 655, the DC voltage stored in the battery 205 can be output, and the inverter 420 and the motor 250 operate using this.

[0157] On the other hand, in the charging mode when the vehicle is driving, for example, in the regenerative mode, the filter 620, the relay device 630, the rectifying unit 640, and the converter 650 do not operate. The regenerative power using the inverter 420 and the motor 250 can charge the battery 205 with a DC voltage based on the power or energy movement in the direction of the DC link capacitor 655, the DC / DC converter 670, the filter 680, and the battery 205.

[0158] Figure 7a It is an example of the circuit diagram of the relay device related to the present disclosure, Figure 7b which is Figure 7a the figure referred to in the description of

[0159] Referring to the drawings, the relay device 630x related to the present disclosure may include a current limiter 632, a relay 634x, and a relay drive circuit 638 in order to prevent inrush current between the input AC power supply 201 and the load 690.

[0160] The relay 634x has a relay switch 635 and a relay coil 636.

[0161] Figure 7b Illustrate the output voltage waveform Vrx of the relay drive circuit 638 and the drive waveform Srx of the relay.

[0162] As Figure 7b As shown, when the relay drive circuit 638 is disconnected from the time point Tx1 to the time point Tx2, the relay 634x is disconnected, and the first current based on the input AC power supply 201 is supplied to the load 690 through the current limiter 632.

[0163] On the other hand, when the relay drive circuit 638 operates from the time point Tx2 to the time point Tx3 and outputs the V1 voltage, the relay 634x is turned on, and the second current based on the input AC power supply 201 does not flow through the current limiter 632 but is supplied to the load 690 through the relay 634x.

[0164] On the other hand, when the relay drive circuit 638 operates from the time point Tx2 to the time point Tx3 and outputs the V1 voltage, the relay coil 636 on the secondary side of the relay 634 generates continuous heat due to the level of the V1 voltage. Therefore, the possibility of burnout of the relay 634x becomes greater.

[0165] Therefore, in the present disclosure, a scheme for reducing the heat generation and the possibility of burnout of the relay in the relay device is proposed. For this, refer to Figure 8 The following is a description.

[0166] Figure 8 It is an example of the circuit diagram of the relay device according to an embodiment of the present disclosure.

[0167] Referring to the drawings, the relay device 630a according to an embodiment of the present disclosure includes: a current limiter 632 that limits the current of the input AC power supply 201, a relay 634 with its primary side connected between the first end Na and the second end Nb at both ends of the current limiter 632, a first power supply unit 802 that is connected between the third end Nc, which is the secondary side of the relay 634, and the ground terminal Ng and supplies the first power supply V1, a first switching element SWa that is connected between the fourth end Nd, which is the secondary side of the relay 634, and the ground terminal Ng, and a second power supply unit 804 and a second switching element SWb that are connected in series with each other between the fourth end Nd and the ground terminal Ng.

[0168] On the other hand, the second power supply unit 804 supplies a second power supply V2 that is lower than the first power supply V1.

[0169] On the other hand, the relay 634 has a relay switch 635 on the primary side and a relay coil 636 on the secondary side.

[0170] On the other hand, when the first switching element SWa is turned on and the second switching element SWb is turned off, the first power supply V1 is supplied to the relay 634. When the first switching element SWa is turned off and the second switching element SWb is turned on, the difference between the first power supply V1 and the second power supply V2, i.e., the third power supply V3, is supplied to the relay 634. Thus, as different levels of power supplies are sequentially supplied to the relay 634, heat generation in the relay 634, particularly heat generation in the relay coil 636, can be reduced. Furthermore, surge current can be prevented during battery 205 charging.

[0171] Compared with Figure 7a the relay device 630x, Figure 8 the relay device 630a supplies different levels of power supplies to the relay 634 sequentially. Thereby, heat generation in the relay 634, particularly heat generation in the relay coil 636, can be reduced.

[0172] Figures 9a to 9b is Figure 8 the figure referred to in the description of

[0173] Figure 9a is a figure illustrating the voltage applied to the relay coil 636 based on the operations of the first switching element SWa and the second switching element SWb, Figure 9b illustrating Figure 9a the output voltage waveform Vra of the relay drive circuit 638 and the drive waveform Sra of the relay based on the operations of

[0174] Referring to the drawings, during the period from Ta1 to Ta2, both the first switching element SWa and the second switching element SWb in the relay drive circuit 638 can be turned off.

[0175] When both the first switching element SWa and the second switching element SWb are turned off, the third node Nc is supplied with the first power supply V1, but the fourth node Nd is floating, so a voltage capable of causing operation is not supplied across the relay coil 636 on the secondary side of the relay 634, and thus the relay 634 may be turned off.

[0176] Next, during the period from Ta2 to Ta3, the first switching element SWa in the relay drive circuit 638 can be turned on and the second switching element SWb can be turned off.

[0177] When the first switching element SWa is turned on and the second switching element SWb is turned off, the third node Nc is supplied with the first power supply V1, and the fourth node Nd is connected to ground. As a result, the first power supply V1 is supplied across the relay coil 636 on the secondary side of the relay 634. Therefore, the relay 634 is turned on.

[0178] Next, during the period from Ta3 to Ta4, the first switching element SWa in the relay drive circuit 638 is turned on and the second switching element SWb is turned on.

[0179] When the first switching element SWa is turned on and the second switching element SWb is turned on, the third node Nc is supplied with the first power supply V1, the fourth node Nd is grounded and connected to the second power supply V2, and as a result, the fourth node Nd continuously maintains the grounded state.

[0180] As a result, both ends of the relay coil 636 on the secondary side of the relay 634 are supplied with the first power supply V1. Therefore, the relay 634 is turned on.

[0181] Next, during the period from Ta4 to Ta5, the first switching element SWa in the relay drive circuit 638 is turned off and the second switching element SWb is turned on.

[0182] When the first switching element SWa is turned off and the second switching element SWb is turned on, the third node Nc is supplied with the first power supply V1, and the grounding connection of the fourth node Nd is disconnected and connected to the second power supply V2.

[0183] Therefore, when the first switching element SWa is turned off and the second switching element SWb is turned on, the third node Nc is connected to the first power supply V1, and the fourth node Nd is connected to the second power supply V2.

[0184] As a result, the difference between the first power supply V1 and the second power supply V2, that is, the third power supply V3, is supplied to both ends of the relay coil 636 on the secondary side of the relay 634. Therefore, the relay 634 is turned on.

[0185] On the other hand, during the period from Ta4 to Ta5, even if the relay 634 is turned on, since the third power supply V3 with a level lower than the first power supply V1 is supplied to both ends of the relay coil 636 on the secondary side of the relay 634, the heat generation of the relay 634 can be reduced, and in particular, the heat generation of the relay coil 636 can be reduced.

[0186] In this way, as different levels of power supplies are sequentially supplied to the relay 634, the heat generation of the relay 634 can be reduced.

[0187] That is, based on the operation of the first switching element SWa or the second switching element SWb, the coil 636 in the relay 634 can be sequentially supplied with a plurality of levels of power supplies V1 and V3. In this way, as different levels of power supplies are sequentially supplied to the relay 634, the heat generation of the relay 634 can be reduced.

[0188] On the other hand, the level of the second power supply V2 can be 20% to 60% of the first power supply V1.

[0189] Thus, during the period from Ta4 to Ta5, the difference between the first power supply V1 and the second power supply V2, i.e., the third power supply V3, is supplied to both ends of the relay coil 636 which is the secondary side of the relay 634. At this time, the level of the third power supply V3 can be 40% to 80% of the first power supply V1.

[0190] On the other hand, referring to Figure 9b , on the other hand, during the first time period Ta1 to Ta2, the first current Ia of the input AC power supply 201 flows through the current limiter 632. During the second time period Ta2 to Ta5 after the first time period Ta1 to Ta2, the second current Ib of the input AC power supply 201 flows through the relay 634. Thus, surge current can be prevented during battery charging.

[0191] On the other hand, the level of the second current Ib can be greater than the level of the first current Ia.

[0192] That is, different from the first current Ia flowing through the current limiter 632, the second current Ib flows through the relay 634. Therefore, when the battery 205 is charged, it is not affected by the current limiter 632, and thus the heating of the current limiter 632 or the limitation of the input AC power supply 201 based on the current limiter 632 can be prevented.

[0193] On the other hand, during the second time period Ta2 to Ta5, based on the operation of the first switching element SWa or the second switching element SWb, power supplies V1 and V3 of multiple levels can be sequentially supplied to the coil 636 in the relay 634. In this way, as different levels of power are sequentially supplied to the relay 634, the heating of the relay 634 can be reduced.

[0194] On the other hand, it is also possible to omit Figure 9a and Figure 9b the time period from Ta3 to Ta4, and the first switching element SWa and the second switching element SWb operate.

[0195] That is, during the time period from Ta2 to Ta3, the first switching element SWa is turned on and the second switching element SWb is turned off. After that, the conduction operations of the first switching element SWa and the second switching element SWb are omitted, and immediately during the time period from Ta4 to Ta5, the first switching element SWa is turned off and the second switching element SWb is turned on. In this way, as different levels of power are sequentially supplied to the relay 634, the heating of the relay 634 can be reduced.

[0196] On the other hand, Figure 9a or Figure 9b the operations of the first switching element SWa and the second switching element SWb of Figure 2 can be performed by the control unit 170 of Figure 3is controlled by the inverter control unit 430.

[0197] On the other hand, in Figures 8 to 9b in addition to the first switching element SWa and the second switching element SWb, between the fourth node Nd and the ground terminal Ng, additionally, a third switching element (not shown) and a third power supply unit (not shown) connected in parallel may be provided.

[0198] Thereby, after the Ta5 period, a fourth power supply having a level lower than that of the third power supply can also be supplied to the relay 634. Thus, as the relay 634 is supplied with power supplies of three sequentially decreasing levels, heat generation of the relay 634 can be further reduced.

[0199] Figure 10 is an example of a circuit diagram of a relay device according to another embodiment of the present disclosure.

[0200] Referring to the drawings, a relay device 630b according to another embodiment of the present disclosure includes: a current limiter 632 that limits the current of the input AC power supply 201, a relay 634 having a primary side connected between a first end Na and a second end Nb of the current limiter 632, a power supply unit 637 connected between a third end Nc of the secondary side of the relay 634 and the ground terminal Ng, and a switching element SW connected between a fourth end Nd of the secondary side of the relay 634 and the ground terminal Ng.

[0201] On the other hand, the power supply unit 637 supplies a first power supply V1 and then supplies a second power supply V2 lower than the first power supply V1.

[0202] On the other hand, the relay 634 has a relay switch 635 on the primary side and a relay coil 636 on the secondary side.

[0203] On the other hand, when the switching element SW is turned on, the power supply unit 637 may supply the first power supply V1 and then supply the second power supply V2 lower than the first power supply V1. In this way, as the relay 634 is sequentially supplied with power supplies of different levels, heat generation of the relay 634, particularly heat generation of the relay coil 636, can be reduced. Further, a surge current can be prevented when the battery 205 is charged.

[0204] Compared with Figure 7a the relay device 630x of Figure 10 the relay device 630b of

[0205] Figures 11a to 11b is Figure 10 the figure referred to in the description of

[0206] Figure 11a FIG. illustrating the voltage applied to the relay coil 636 based on the operation of the switching element SW and the switching element SW. Figure 11b Illustrating based on Figure 11a The output voltage waveform Vrb of the relay drive circuit 638 and the drive waveform Srb of the relay based on the operation of.

[0207] Referring to the drawings, during the time period from Tb1 to Tb2, the switching element SW in the relay drive circuit 638 can be turned off.

[0208] When the switching element SW is turned off, the third node Nc is supplied with the first power supply V1, but since the fourth node Nd is floating, a voltage capable of operating is not supplied to both ends of the relay coil 636 on the secondary side of the relay 634. Therefore, the relay 634 may be turned off.

[0209] Next, during the time period from Tb2 to Tb4, the switching element SW in the relay drive circuit 638 can be turned on, and the power supply unit 637 can supply the first power supply V1.

[0210] When the switching element SW is turned on, the third node Nc is supplied with the first power supply V1, and the fourth node Nd is grounded. As a result, the first power supply V1 is supplied to both ends of the relay coil 636 on the secondary side of the relay 634. Therefore, the relay 634 is turned on.

[0211] Next, during the time period from Tb4 to Tb5, the switching element SW in the relay drive circuit 638 is turned on, and the power supply unit 637 can supply a second power supply V2 lower than the first power supply V1.

[0212] When the switching element SW is turned on, the third node Nc is supplied with the second power supply V2, and the fourth node Nd is grounded. As a result, the second power supply V2 is supplied to both ends of the relay coil 636 on the secondary side of the relay 634. Therefore, the relay 634 is turned on.

[0213] On the other hand, during the time period from Tb4 to Tb5, even if the relay 634 is turned on, since the second power supply V2 having a level lower than the first power supply V1 is supplied to both ends of the relay coil 636 on the secondary side of the relay 634, heat generation of the relay 634 can be reduced, particularly heat generation of the relay coil 636.

[0214] In this way, as the relay 634 is sequentially supplied with power supplies of different levels, heat generation of the relay 634 can be reduced.

[0215] On the other hand, referring to Figure 11b, on the other hand, during the first time period Tb1 to Tb2, the first current Ia of the input AC power supply 201 flows through the current limiter 632, and during the second time period Tb2 to Tb5 after the first time period Tb1 to Tb2, the second current Ib of the input AC power supply 201 flows through the relay 634. Thus, surge current can be prevented during battery charging.

[0216] On the other hand, the second current Ib level can be greater than the first current Ia level.

[0217] That is, different from the first current Ia flowing through the current limiter 632, the second current Ib flows through the relay 634. Therefore, when the battery 205 is charged, it is not affected by the current limiter 632, and thus heat generation of the current limiter 632 or the limitation of the input AC power supply 201 based on the current limiter 632 can be prevented.

[0218] On the other hand, during the second time period Tb2 to Tb5, based on the operation of the switching element SW, power supplies V1 and V2 of multiple levels can be sequentially supplied to the coil 636 in the relay 634. Thus, as different levels of power are sequentially supplied to the relay 634, heat generation of the relay 634 can be reduced.

[0219] Although the preferred embodiments of the present disclosure have been illustrated and described above, the present disclosure is not limited to the above specific embodiments, and those skilled in the art can implement various modifications without departing from the gist of the present disclosure claimed in the claims. Such modified implementations should not be understood separately from the technical idea or prospect of the present disclosure.

Claims

1. A relay device, wherein, Comprising: A current limiter that limits the current of an input AC power supply; A relay, the primary side of which is connected between the two ends of the current limiter, namely between the first end and the second end; A first power supply unit, connected between the third end, which is the secondary side of the relay, and the ground terminal, and supplies a first power supply; A first switching element, connected between the fourth end, which is the secondary side of the relay, and the ground terminal; And A second power supply unit and a second switching element, which are connected in series between the fourth end and the ground terminal; The second power supply unit supplies a second power supply that is lower than the first power supply.

2. The relay device according to claim 1, wherein When the first switching element is turned on and the second switching element is turned off, the first power supply is supplied to the relay, When the first switching element is turned off and the second switching element is turned on, the difference between the first power supply and the second power supply, namely the third power supply, is supplied to the relay.

3. The relay device according to claim 1, wherein When the first switching element is turned on and the second switching element is turned off, the first power supply is supplied to the relay, When the first switching element is turned on and the second switching element is turned on, the first power supply is supplied to the relay, When the first switching element is turned off and the second switching element is turned on, the difference between the first power supply and the second power supply, namely the third power supply, is supplied to the relay.

4. The relay device according to claim 1, wherein Based on the operation of the first switching element or the second switching element, power supplies of multiple levels are sequentially supplied to the coil in the relay.

5. The relay device according to claim 1, wherein During a first time period, a first current based on the input AC power supply flows through the current limiter, During a second time period after the first time period, a second current based on the input AC power supply flows through the relay.

6. The relay device according to claim 5, wherein The second current level is greater than the first current level.

7. The relay device according to claim 5, wherein During the second time period, based on the operation of the first switching element or the second switching element, power supplies of multiple levels are sequentially supplied to the coil in the relay.

8. A relay device, wherein, Comprising: A current limiter that limits the current of an input AC power supply; A relay, the primary side of which is connected between the two ends of the current limiter, namely between the first end and the second end; A power supply unit, connected between the third end, which is the secondary side of the relay, and the ground terminal; And A switching element, connected between the fourth end, which is the secondary side of the relay, and the ground terminal; The power supply unit supplies a first power supply and then supplies a second power supply that is lower than the first power supply.

9. The relay device according to claim 8, wherein When the switching element is turned on, the first power supply is supplied to the relay, and then a second power supply that is lower than the first power supply is supplied to the relay.

10. The relay device according to claim 8, wherein During a first period, a first current based on the input AC power supply flows through the current limiter. During a second period after the first period, a second current based on the input AC power supply flows through the relay.

11. The relay device according to claim 10, wherein the second current level is greater than the first current level.

12. The relay device according to claim 10, wherein during the second period, power supplies of a plurality of levels are sequentially supplied to a coil in the relay based on the operation of the switching element.

13. A battery charging device, wherein, Comprising the relay device according to any one of claims 1 to 12.

14. The battery charging device according to claim 13, wherein, Further comprising: a rectifying unit that rectifies the AC power supply from the relay device; a converter that converts the power supply from the rectifying unit into a DC power supply; a DC link capacitor disposed at an output end of the converter.

15. The battery charging device according to claim 14, wherein, Further comprising a DC / DC converter that converts the level of the DC voltage of the DC link capacitor.

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