Motor drive device and air conditioner including same

Abstract

The invention relates to a motor driving device and an air conditioner having the same. A motor driving device according to an embodiment of the present invention comprises: a rectifying unit that rectifies a three-phase AC voltage; a capacitor for storing the pulsating voltage from the rectifying unit; a harmonic reduction unit that is disposed between the rectification unit and the capacitor, has at least one switching element, and performs harmonic reduction of the three-phase AC voltage; and an inverter having a plurality of switching elements and outputting the converted AC voltage to the motor using the voltage across the capacitor. The harmonic reduction unit is turned on or off on the basis of the output power of the inverter. Consequently, harmonics of the input current based on the three-phase AC voltage can be reduced.

Description

Technical Field

[0001] The present invention relates to a motor drive device and an air conditioner having the same, and more particularly to a motor drive device capable of reducing harmonics of an input current based on a three-phase AC voltage and an air conditioner having the same. Background Art

[0002] Air conditioners create a comfortable indoor environment by blowing out hot and cold air into the room, regulating the indoor temperature and purifying the air. Typically, an air conditioner consists of an indoor unit, which consists of a heat exchanger and is installed indoors, and an outdoor unit, which includes a compressor and heat exchanger and supplies refrigerant to the indoor unit.

[0003] On the other hand, a compressor motor driving device is used to drive the compressor of the air conditioner.

[0004] The compressor motor drive device converts input AC voltage into DC voltage, stores the converted DC voltage in a capacitor, and uses the DC voltage stored in the capacitor to operate an inverter to drive the compressor motor.

[0005] Recently, there has been a trend toward using film capacitors rather than electrolytic capacitors to reduce the size of capacitors in compressor motor drive devices.

[0006] However, film capacitors have a smaller capacitance than electrolytic capacitors, so the ripple of the voltage stored in the capacitor becomes larger, and the harmonic components of the input AC voltage increase.

[0007] On the other hand, according to the international surge protection standard IEC 61000-3-12, based on harmonic regulation, it is necessary to meet the total harmonic distortion (THD) and partial weighted harmonic distortion (PWHD) regulations.

[0008] Conventional document Korean Patent Publication No. 10-1905480 discloses a harmonic reduction unit for reducing harmonics as a motor drive device and an air conditioner having the same.

[0009] However, existing documents disclose that only harmonics of the 14th order and above are compensated, so that the 5th, 7th, 11th, and 13th order input harmonic components are not compensated, thereby causing a problem of harmonic distortion of the current flowing through the inverter. Summary of the Invention

[0010] The present invention solves the problem by providing a motor drive device capable of reducing harmonics of an input current based on a three-phase AC voltage, and an air conditioner having the motor drive device.

[0011] Another problem to be solved by the present invention is to provide a motor drive device capable of effectively reducing harmonics of a specific order of input current based on a three-phase AC voltage, and an air conditioner having the motor drive device.

[0012] Another problem to be solved by the present invention is to provide a motor drive device capable of reducing harmonic distortion of current flowing through an inverter, and an air conditioner having the motor drive device.

[0013] Another problem to be solved by the present invention is to provide a motor drive device capable of reducing harmonics without detecting input current when a three-phase AC voltage is input, and an air conditioner having the motor drive device.

[0014] The motor drive device of an embodiment of the present invention for achieving the above-mentioned solution to the problem and the air conditioner having the motor drive device include: a rectifier unit that rectifies a three-phase AC voltage; a capacitor that stores a pulsating voltage from the rectifier unit; a harmonic reduction unit that is arranged between the rectifier unit and the capacitor, has at least one switching element, and performs harmonic reduction of the three-phase AC voltage; and an inverter that has a plurality of switching elements and uses the voltage across the capacitor to output the converted AC voltage to the motor; the harmonic reduction unit is turned on or off based on the output power of the inverter.

[0015] On the other hand, the harmonic reduction portion may be turned off based on an increase and a decrease in the output power of the inverter, and may be turned on based on a decrease and an increase in the output power of the inverter.

[0016] On the other hand, the harmonic reduction unit may be turned on based on an increase in the output power of the inverter.

[0017] On the other hand, the harmonic reduction unit can be turned on in the first period based on the increase of the output power of the inverter, can be turned off in the second period based on the increase and decrease of the output power of the inverter, and can be turned on in the third period based on the decrease and increase of the output power of the inverter.

[0018] On the other hand, the ripple voltage stored in the capacitor can be made smaller when the harmonic reduction unit is turned off than when the harmonic reduction unit is turned on.

[0019] On the other hand, the motor drive device of an embodiment of the present invention and the air conditioner having the motor drive device further include: a voltage detection unit for detecting the pulsating voltage stored in the capacitor; and a control unit for controlling the operation of the harmonic reduction unit; the control unit can control the switching of the switching element in the harmonic reduction unit based on the 6th or 12th harmonic component of the pulsating voltage.

[0020] On the other hand, the control unit may generate a current command based on the sixth or twelfth harmonic component of the ripple voltage, and may control the operation of the harmonic reduction unit based on the generated current command.

[0021] On the other hand, the control unit may control the on-duty ratio of the switching element in the harmonic reduction unit to increase as the sixth or twelfth harmonic component of the pulsating voltage increases.

[0022] On the other hand, the control unit may include: a first filter for filtering a DC component of the pulsating voltage; and a second filter for filtering a 6th or 12th harmonic component of the pulsating voltage.

[0023] On the other hand, the control unit may include: a first filter for filtering a DC component of the pulsating voltage; a second filter for filtering a 6th or 12th harmonic component of the pulsating voltage; and a third filter for filtering a 40th or lower harmonic component of the pulsating voltage.

[0024] On the other hand, the harmonic reduction unit may include an inductor, a first switching element, and a second capacitor connected between both ends of the capacitor; and a second switching element connected between the inductor and the first switching element and between the second capacitor and the capacitor.

[0025] On the other hand, the motor drive device of an embodiment of the present invention and the air conditioner having the motor drive device also include: a voltage detection unit, which detects the pulsating voltage stored in the capacitor; and a control unit, which controls the operation of the harmonic reduction unit; the control unit can extract harmonic components below the 40th order of the pulsating voltage, and can control the harmonic reduction unit based on the extracted harmonic voltage.

[0026] On the other hand, the control unit includes: a current command generating unit that extracts harmonic components of the pulsating voltage below the 40th order; a power command generating unit that generates a power command value based on the harmonic voltage below the 40th order; and a voltage command generating unit that generates a compensation voltage command value based on the generated power command value; the operation of the first switching element or the second switching element in the harmonic reduction unit can be controlled based on the compensation voltage command value.

[0027] In another aspect, the capacitor may comprise a film capacitor.

[0028] On the other hand, the motor drive device of an embodiment of the present invention and the air conditioner having the motor drive device may further include: a voltage detection unit for detecting the pulsating voltage stored in the capacitor; a control unit for controlling the operation of the harmonic reduction unit; and an inverter control unit for controlling the inverter.

[0029] On the other hand, the motor drive device of an embodiment of the present invention and the air conditioner having the motor drive device also include: a first voltage detection unit for detecting a pulsating voltage stored in a capacitor; a current detection unit for detecting a current flowing in the harmonic reduction unit; a second voltage detection unit for detecting a voltage across a second capacitor in the harmonic reduction unit; and a control unit for controlling the harmonic reduction unit based on the pulsating voltage from the first voltage detection unit, the detected current from the current detection unit, and the detected voltage from the second voltage detection unit.

[0030] On the other hand, the harmonic reduction unit, the current detection unit, the first voltage detection unit, the second voltage detection unit, and the control unit may be arranged on a first circuit board, and the inverter may be arranged on a second circuit board separate from the first circuit board.

[0031] On the other hand, the motor drive device of an embodiment of the present invention and the air conditioner having the motor drive device also include a second current detection unit that detects a second current flowing between the capacitor and the inverter, and the control unit can control the harmonic reduction unit based on the pulsating voltage from the first voltage detection unit, the detected current from the current detection unit, the detected voltage from the second voltage detection unit, and the second current from the second current detection unit.

[0032] On the other hand, the motor drive device of an embodiment of the present invention and the air conditioner having the motor drive device also include a third current detection unit that detects a third current flowing between the rectifier unit and the capacitor, and the control unit can control the harmonic reduction unit based on the pulsating voltage from the first voltage detection unit, the detection current from the current detection unit, the detection voltage from the second voltage detection unit, and the third current from the third current detection unit.

[0033] A motor drive device according to another embodiment of the present invention and an air conditioner having the motor drive device include: a rectifier unit that rectifies a three-phase AC voltage; a capacitor that stores a pulsating voltage from the rectifier unit; a harmonic reduction unit that is arranged between the rectifier unit and the capacitor, has at least one switching element, and performs harmonic reduction of the three-phase AC voltage; an inverter that has a plurality of switching elements and uses the voltage across the capacitor to output the converted AC voltage to the motor; a voltage detection unit that detects the pulsating voltage stored in the capacitor; and a control unit that controls the operation of the harmonic reduction unit; the control unit can control the switching of the switching elements in the harmonic reduction unit based on the 6th or 12th harmonic components of the pulsating voltage.

[0034] On the other hand, the control unit may control the on-duty ratio of the switching element in the harmonic reduction unit to increase as the sixth or twelfth harmonic component of the pulsating voltage increases.

[0035] On the other hand, the control unit may include: a first filter for filtering a DC component of the pulsating voltage; and a second filter for filtering a 6th or 12th harmonic component of the pulsating voltage.

[0036] On the other hand, the harmonic reduction unit may include an inductor, a first switching element, and a second capacitor connected between both ends of the capacitor; and a second switching element connected between the inductor and the first switching element and between the second capacitor and the capacitor.

[0037] A motor drive device and an air conditioner equipped with the same according to an embodiment of the present invention include: a rectifier that rectifies a three-phase AC voltage; a capacitor that stores a pulsating voltage from the rectifier; a harmonic reduction unit disposed between the rectifier and the capacitor and having at least one switching element to reduce harmonics in the three-phase AC voltage; and an inverter having a plurality of switching elements that uses the voltage across the capacitor to output the converted AC voltage to the motor. The harmonic reduction unit is turned on and off based on the output power of the inverter. This reduces harmonics in the input current based on the three-phase AC voltage.

[0038] On the other hand, the harmonic reduction unit can be turned off based on the increase and decrease of the output power of the inverter, and can be turned on based on the decrease and increase of the output power of the inverter. In this way, the harmonics of the input current based on the three-phase AC voltage can be reduced.

[0039] On the other hand, the harmonic reduction unit may be turned on in response to an increase in the output power of the inverter, thereby reducing harmonics of the input current based on the three-phase AC voltage.

[0040] On the other hand, the harmonic reduction unit can be turned on during a first period as the inverter output power increases, turned off during a second period as the inverter output power increases and decreases, and turned on during a third period as the inverter output power decreases and increases. This reduces harmonics in the input current based on the three-phase AC voltage.

[0041] On the other hand, the ripple voltage stored in the capacitor can be made smaller when the harmonic reduction unit is turned off than when the harmonic reduction unit is turned on. This can reduce the harmonics of the input current based on the three-phase AC voltage.

[0042] In another aspect, a motor drive device and an air conditioner equipped with the same according to an embodiment of the present invention further include a voltage detection unit for detecting a pulsating voltage stored in a capacitor; and a control unit for controlling the operation of a harmonic reduction unit. The control unit can control the switching of a switching element within the harmonic reduction unit based on the 6th or 12th harmonic component of the pulsating voltage. This effectively reduces harmonics of specific orders in the input current based on the three-phase AC voltage. Furthermore, it reduces harmonic distortion of the current flowing through the inverter.

[0043] Alternatively, the control unit can generate a current command based on the 6th or 12th harmonic component of the pulsating voltage and control the operation of the harmonic reduction unit based on the generated current command. This effectively reduces harmonics of specific orders in the input current based on the three-phase AC voltage.

[0044] Alternatively, the control unit may control the switching element in the harmonic reduction unit to increase its on-duty ratio as the 6th or 12th harmonic component of the pulsating voltage increases. This effectively reduces harmonics of a specific order in the input current based on the three-phase AC voltage.

[0045] On the other hand, the control unit may include: a first filter for filtering the DC component of the pulsating voltage; and a second filter for filtering the 6th or 12th harmonic components of the pulsating voltage. This can effectively reduce harmonics of a specific order of the input current based on the three-phase AC voltage.

[0046] On the other hand, the control unit can include: a first filter for filtering the DC component of the pulsating voltage; a second filter for filtering the 6th or 12th harmonic components of the pulsating voltage; and a third filter for filtering the 40th and lower harmonic components of the pulsating voltage. This effectively reduces harmonics of specific orders in the input current based on the three-phase AC voltage.

[0047] On the other hand, the harmonic reduction unit may include: an inductor, a first switching element, and a second capacitor connected between both ends of the capacitor; and a second switching element connected between the inductor and the first switching element and between the second capacitor and the capacitor. This reduces harmonics in the input current based on the three-phase AC voltage.

[0048] In another aspect, a motor drive device and an air conditioner equipped with the motor drive device according to an embodiment of the present invention further include a voltage detection unit for detecting a pulsating voltage stored in a capacitor; and a control unit for controlling the operation of the harmonic reduction unit. The control unit is configured to extract harmonic components of the pulsating voltage up to the 40th order and control the harmonic reduction unit based on the extracted harmonic voltage. This reduces harmonics in the input current based on the three-phase AC voltage.

[0049] Meanwhile, the control unit includes a current command generator that extracts harmonic components of the ripple voltage up to the 40th order; a power command generator that generates a power command value based on the harmonic voltage up to the 40th order; and a voltage command generator that generates a compensation voltage command value based on the generated power command value. The operation of the first switching element or the second switching element in the harmonic reduction unit can be controlled based on the compensation voltage command value. This reduces harmonics in the input current based on the three-phase AC voltage.

[0050] In another aspect, the motor drive device and air conditioner equipped with the motor drive device according to an embodiment of the present invention may further include a voltage detection unit for detecting the pulsating voltage stored in the capacitor; a control unit for controlling the operation of the harmonic reduction unit; and an inverter control unit for controlling the inverter. This reduces harmonics in the input current based on the three-phase AC voltage.

[0051] On the other hand, a motor drive device and an air conditioner equipped with the motor drive device according to an embodiment of the present invention further include: a first voltage detection unit for detecting a pulsating voltage stored in a capacitor; a current detection unit for detecting a current flowing in a harmonic reduction unit; a second voltage detection unit for detecting a voltage across a second capacitor in the harmonic reduction unit; and a control unit for controlling the harmonic reduction unit based on the pulsating voltage from the first voltage detection unit, the current detected by the current detection unit, and the voltage detected by the second voltage detection unit. This allows harmonic reduction without requiring input current detection when a three-phase AC voltage is input.

[0052] Alternatively, the harmonic reduction unit, current detection unit, first voltage detection unit, second voltage detection unit, and control unit may be arranged on a first circuit board, while the inverter may be arranged on a second circuit board separate from the first circuit board. As described above, by arranging the inverter and harmonic reduction unit on separate circuit boards, the harmonic reduction unit can operate effectively.

[0053] In another embodiment of the present invention, the motor drive device and air conditioner equipped with the motor drive device further include a second current detection unit that detects a second current flowing between the capacitor and the inverter. The control unit can control the harmonic reduction unit based on the ripple voltage from the first voltage detection unit, the detected current from the current detection unit, the detected voltage from the second voltage detection unit, and the second current from the second current detection unit. This allows harmonic reduction without requiring input current detection when a three-phase AC voltage is input.

[0054] In another embodiment of the present invention, the motor drive device and air conditioner equipped with the motor drive device further include a third current detection unit that detects a third current flowing between the rectifier unit and the capacitor. The control unit can control the harmonic reduction unit based on the pulsating voltage from the first voltage detection unit, the detected current from the current detection unit, the detected voltage from the second voltage detection unit, and the third current from the third current detection unit. This allows harmonic reduction without requiring input current detection when a three-phase AC voltage is input.

[0055] A motor drive device and an air conditioner equipped with the same according to another embodiment of the present invention include: a rectifier for rectifying a three-phase AC voltage; a capacitor for storing a pulsating voltage from the rectifier; a harmonic reduction unit, disposed between the rectifier and the capacitor and having at least one switching element, for reducing harmonics in the three-phase AC voltage; an inverter, having a plurality of switching elements, for outputting the converted AC voltage to a motor using the voltage across the capacitor; a voltage detection unit for detecting the pulsating voltage stored in the capacitor; and a control unit for controlling the operation of the harmonic reduction unit. The control unit can control the switching of the switching elements in the harmonic reduction unit based on the 6th or 12th harmonic components of the pulsating voltage. This reduces harmonics in the input current based on the three-phase AC voltage. In particular, harmonics of specific orders in the input current based on the three-phase AC voltage can be effectively reduced. Furthermore, harmonic distortion of the current flowing through the inverter can be reduced.

[0056] Alternatively, the control unit may control the switching element in the harmonic reduction unit to increase its on-duty ratio as the 6th or 12th harmonic component of the pulsating voltage increases. This effectively reduces harmonics of a specific order in the input current based on the three-phase AC voltage.

[0057] On the other hand, the control unit may include: a first filter for filtering the DC component of the pulsating voltage; and a second filter for filtering the 6th or 12th harmonic components of the pulsating voltage. This can effectively reduce harmonics of a specific order of the input current based on the three-phase AC voltage.

[0058] On the other hand, the harmonic reduction unit may include: an inductor, a first switching element, and a second capacitor connected between both ends of the capacitor; and a second switching element connected between the inductor and the first switching element and between the second capacitor and the capacitor. This reduces harmonics in the input current based on the three-phase AC voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a diagram illustrating the configuration of an air conditioner according to an embodiment of the present invention.

[0060] Figure 2 yes Figure 1 Schematic diagram of the outdoor unit and indoor unit.

[0061] Figure 3 Is used to drive Figure 1 An example of a block diagram of a motor drive device for a compressor in an outdoor unit.

[0062] Figure 4 yes Figure 3 An example of an internal block diagram of the control unit.

[0063] Figure 5This is an example of a motor drive device.

[0064] Figures 6a to 6d It is explaining Figure 3 Refer to the figure when using the motor drive device.

[0065] Figure 7 This is an example of a circuit diagram of a motor drive device according to an embodiment of the present invention.

[0066] Figures 8 to 15 It is explaining Figure 7 Refer to the figure when using .

[0067] Figure 16 This is an example of a circuit diagram of a motor drive device according to another embodiment of the present invention.

[0068] Figure 17 This is an example of a circuit diagram of a motor drive device according to another embodiment of the present invention.

[0069] Figure 18 It is an explanation Figure 17 Refer to the figure when using .

[0070] Figure 19 This is an example of a circuit diagram of a motor drive device according to another embodiment of the present invention.

[0071] Figure 20 This is an example of a circuit diagram of a motor drive device according to another embodiment of the present invention. DETAILED DESCRIPTION

[0072] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

[0073] The suffixes "module" and "unit" used in the following description of the structural elements are only given for the convenience of writing this specification and do not themselves have any particularly important meaning or function. Therefore, the above "module" and "unit" can be used interchangeably.

[0074] Figure 1 This is a diagram illustrating the configuration of an air conditioner according to an embodiment of the present invention.

[0075] like Figure 1 As shown, the air conditioner of the present invention is a large air conditioner 50, which may include: a plurality of indoor units 31, 32, 33, 34, 35; a plurality of outdoor units 21, 22, connected to the plurality of indoor units; remote controllers 41, 42, 43, 44, 45, respectively connected to the plurality of indoor units; and a remote controller 10, which controls the plurality of indoor units and outdoor units.

[0076] The remote controller 10 is connected to the plurality of indoor units 31, 32, 33, 34, 35 and the plurality of outdoor units 21, 22 to monitor and control their operations. The remote controller 10 can be connected to the plurality of indoor units to perform operation settings, lock settings, schedule control, group control, etc. on the indoor units.

[0077] The air conditioner can be any of a floor-standing type, a wall-mounted type, or a ceiling-mounted type. However, for ease of explanation, the following description uses a ceiling-mounted type as an example. Furthermore, the air conditioner may include at least one of a ventilation device, an air purifier, a humidifier, and a heater, and may operate in conjunction with the operation of the indoor and outdoor units.

[0078] Outdoor units 21 and 22 consist of a compressor (not shown) that receives and compresses refrigerant; an outdoor heat exchanger (not shown) that exchanges heat between the refrigerant and the outdoor air; a liquid accumulator (not shown) that extracts gaseous refrigerant from the received refrigerant and supplies it to the compressor; and a four-way valve (not shown) that selects the refrigerant flow path for heating operation. They also include a number of sensors, valves, and an oil recovery device, but their structures are omitted in the following description.

[0079] The outdoor units 21 and 22 operate their installed compressors and outdoor heat exchangers to compress or heat-exchange the refrigerant according to settings, supplying refrigerant to the indoor units 31, 32, 33, 34, and 35. The outdoor units 21 and 22 are driven in response to requests from the remote controller 10 or the indoor units 31, 32, 33, 34, and 35. As the cooling or heating capacity changes in response to the indoor units being driven, the number of outdoor units operating and the number of compressors installed in the outdoor units operating change.

[0080] At this time, although the outdoor units 21 and 22 are described as an example in which a plurality of outdoor units supply refrigerant to the respectively connected indoor units, the plurality of outdoor units may be connected to each other according to the connection structure of the outdoor units and the indoor units to supply refrigerant to the plurality of indoor units.

[0081] The indoor units 31, 32, 33, 34, and 35 are connected to any of the multiple outdoor units 21 and 22, receive refrigerant, and discharge hot or cold air into the room. Each of the indoor units 31, 32, 33, 34, and 35 includes an indoor heat exchanger (not shown), an indoor fan (not shown), an expansion valve (not shown) that expands the supplied refrigerant, and multiple sensors (not shown).

[0082] At this time, the outdoor units 21 and 22 and the indoor units 31 , 32 , 33 , 34 , and 35 are connected via communication lines to exchange data with each other. The outdoor units and indoor units are connected to the remote controller 10 via other communication lines and operate according to the control of the remote controller 10 .

[0083] Remote controllers 41, 42, 43, 44, and 45 can each be connected to an indoor unit to input user control commands to the indoor unit and receive and display indoor unit status information. The remote controllers communicate via wired or wireless communication, depending on the connection method with the indoor unit. Depending on the situation, a single remote controller can be connected to multiple indoor units, allowing the settings of multiple indoor units to be changed through input from a single remote controller.

[0084] In addition, the remote controllers 41 , 42 , 43 , 44 , 45 may include temperature sensing sensors therein.

[0085] Figure 2 yes Figure 1 Schematic diagram of the outdoor unit and indoor unit.

[0086] Referring to the drawings, the air conditioner 50 is roughly divided into an indoor unit 31 and an outdoor unit 21 .

[0087] The outdoor unit 21 includes: a compressor 102, which compresses the refrigerant; a compressor motor 102b, which drives the compressor; an outdoor heat exchanger 104, which dissipates heat from the compressed refrigerant; an outdoor blower 105, which is arranged on one side of the outdoor heat exchanger 104 and consists of an outdoor fan 105a for promoting heat dissipation of the refrigerant and a motor 105b for rotating the outdoor fan 105a; an expansion mechanism 106, which expands the condensed refrigerant; a cooling and heating switching valve 110, which switches the flow path of the compressed refrigerant; and a liquid accumulator 103, which temporarily stores the vaporized refrigerant and removes moisture and impurities before supplying the refrigerant at a specified pressure to the compressor.

[0088] The indoor unit 31 includes: an indoor heat exchanger 108, which is arranged indoors and performs cooling and heating functions; and an indoor blower 109, which is arranged on one side of the indoor heat exchanger 108 and consists of an indoor fan 109a that promotes heat dissipation of the refrigerant and a motor 109b that rotates the indoor fan 109a.

[0089] At least one indoor heat exchanger 108 may be provided. The compressor 102 may be at least one of an inverter compressor and a fixed speed compressor.

[0090] The air conditioner 50 may be composed of a refrigerator for cooling the room, or a heat pump for cooling or heating the room.

[0091] on the other hand, Figure 2 An indoor unit 31 and an outdoor unit 21 are shown, but the driving device of the air conditioner according to the embodiment of the present invention is not limited thereto and can also be applied to a multi-type air conditioner having a plurality of indoor units and outdoor units, an air conditioner having an indoor unit and a plurality of outdoor units, etc.

[0092] Figure 1 The compressor 102 in the outdoor unit 21 can be driven by a motor driving device 200 for driving the compressor, and the motor driving device 200 is used to drive the compressor motor 250.

[0093] Figure 3 Is used to drive Figure 1 An example of a block diagram of a motor drive device for a compressor in an outdoor unit.

[0094] first, Figure 3 The motor driving device 200 may include: an inverter 220 outputting a three-phase AC current to the compressor motor 250 ; a converter 210 supplying a DC voltage to the inverter 220 ; and a control unit 230 controlling the converter 210 or the inverter 220 .

[0095] The motor driving device 200 receives an AC voltage from a power system, performs power conversion, and supplies the converted power to the compressor motor 250. Therefore, the motor driving device 200 may also be referred to as a power conversion device or a compressor driving device.

[0096] On the other hand, the motor driving device according to the embodiment of the present invention uses a low-capacity DC terminal capacitor C of less than tens of μF. For example, the low-capacity DC terminal capacitor C may include a film capacitor instead of an electrolytic capacitor.

[0097] When a low-capacity capacitor is used, the DC terminal voltage changes greatly and pulsates, and a smoothing operation is hardly performed.

[0098] Such a motor drive device having a low-capacity DC terminal capacitor C of several tens of μF or less can be called a capacitor-less motor drive device.

[0099] In this specification, the motor driving device 200 including the dc terminal capacitor C with a low capacitance is mainly described.

[0100] On the other hand, according to the present invention, the converter 210 that supplies the DC voltage to the inverter 220 receives the three-phase AC voltage and converts it into a DC voltage. To this end, the converter 210 may include a rectifier ( Figure 7 510).

[0101] Rectification unit( Figure 7 510) receives the three-phase AC voltage 201, rectifies it, and outputs the rectified power. When the three-phase AC voltage 201 is a three-phase AC voltage, the rectifier 510 can rectify the three-phase AC voltage and output it.

[0102] On the other hand, considering the pulsating DC terminal capacitor C, the converter 210 may further include a boost converter for increasing the voltage.

[0103] The output terminal of the converter 210 is connected to a DC terminal capacitor C. The DC terminal capacitor C can store a pulsating voltage output from the converter 210. Since the voltage output from the converter 210 is a DC voltage, it can be referred to as a DC terminal capacitor.

[0104] The input voltage detection unit A can detect the input voltage Vs from the three-phase AC voltage 201 . For example, it can be located at the front end of the converter 210 .

[0105] To detect the voltage, the input voltage detection unit A may include a resistor, an OP AMP, etc. The detected input voltage Vs may be applied to the control unit 230 as a discrete signal in a pulse form.

[0106] On the other hand, the input voltage detection unit A can also detect the zero-cross position of the input voltage.

[0107] Next, the input current detection unit D can detect the input current Is from the three-phase AC voltage 201 . Specifically, it can be located at the front end of the converter 210 .

[0108] To detect the current, the input current detection unit D may include a current sensor, a CT (current transformer), a shunt resistor, etc. The detected input current Is may be applied to the control unit 230 as a discrete signal in a pulse form.

[0109] The DC-side voltage detection unit B detects the pulsating voltage Vdc of the DC-side capacitor C. A resistor, an OP AMP, or the like can be used to detect the voltage. The detected voltage Vdc of the DC-side capacitor C is applied to the control unit 230 as a pulse-shaped discrete signal. Based on the DC voltage Vdc of the DC-side capacitor C, the inverter switching control signal Sic is generated.

[0110] The inverter 220 includes a plurality of inverter switching elements, and can convert the smoothed DC voltage Vdc into a three-phase AC voltage of a predetermined frequency by turning the switching elements on and off, and output the converted voltage to the three-phase motor 250 .

[0111] Specifically, inverter 220 may include a plurality of switching elements. For example, upper arm switching elements Sa, Sb, and Sc, and lower arm switching elements S'a, S'b, and S'c, each connected in series, may form a pair. A total of three pairs of upper and lower arm switching elements (Sa & S'a, Sb & S'b, and Sc & S'c) may be connected in parallel. Furthermore, a diode may be connected in antiparallel to each of the switching elements Sa, S'a, Sb, S'b, Sc, and S'c.

[0112] In order to control the switching operation of the inverter 220, the control unit 230 may output an inverter switching control signal Sic to the inverter 220. The inverter switching control signal Sic is a switching control signal of a pulse width modulation (PWM) method and may be based on the output current i flowing in the motor 250. o Or the DC terminal voltage Vdc across the DC terminal capacitor is generated and output. The output current i o The output current can be detected by the output current detection unit E, and the DC terminal voltage Vdc can be detected by the DC terminal voltage detection unit B.

[0113] The output current detection unit E can detect the output current i flowing between the inverter 220 and the motor 250. o That is, the current flowing in the motor 250 is detected. The output current detection unit E may detect the output current ia, ib, ic of each phase, or may detect the output current of two phases using the three-phase balance.

[0114] The output current detection unit E may be located between the inverter 220 and the motor 250 . To detect the current, a CT (current transformer), a shunt resistor, or the like may be used.

[0115] Figure 4 yes Figure 3 An example of an internal block diagram of the control unit.

[0116] Reference Figure 4 The control unit 230 may include an axis conversion unit 310 , a speed calculation unit 320 , a current command generation unit 330 , a voltage command generation unit 340 , an axis conversion unit 350 , and a switch control signal output unit 360 .

[0117] The axis conversion unit 310 receives the three-phase output currents ia, ib, and ic detected by the output current detection unit E, and converts them into two-phase currents iα and iβ in a stationary coordinate system.

[0118] On the other hand, the axis conversion unit 310 can convert the two-phase currents iα and iβ in the stationary coordinate system into the two-phase currents i d 、i q .

[0119] The speed calculation unit 320 estimates the rotor position of the motor 250 based on the two-phase currents iα and iβ in the stationary coordinate system transformed by the axis transformation unit 310. In addition, the estimated rotor position can be output Calculation speed

[0120] On the other hand, the current command generating unit 330 calculates the speed based on and the target speed ω to calculate the speed command value ω * r , and based on the speed command value ω * r Generate current command value i * q For example, the current command generating unit 330 may calculate the speed based on The speed command value ω is the difference from the target speed ω * r The PI controller 335 performs PI control and generates a current command value i * q In the figure, the q-axis current command value i is shown as an example of the current command value. * q However, unlike the figure, the d-axis current command value i may be generated together. * d On the other hand, the d-axis current command value i * d The value can also be set to 0.

[0121] On the other hand, the current command generating unit 330 may further include a limiter (not shown) for limiting the current command value i * q level to prevent the current command value i * q Exceeds the allowed range.

[0122] Next, the voltage command generating unit 340 generates a voltage command based on the d-axis and q-axis currents i that are converted into the two-phase rotating coordinate system by the axis conversion unit. d 、i q and the current command value i from the current command generating unit 330 and the like. * d 、i * q , generate d-axis and q-axis voltage command values v * d 、v * q For example, the voltage command generating unit 340 may generate the voltage command based on the q-axis current i q and q-axis current command value i* q The PI controller 344 performs PI control and generates a q-axis voltage command value v * q In addition, the voltage command generating unit 340 may be based on the d-axis current i d and the d-axis current command value i * d The PI controller 300 performs PI control and generates a d-axis voltage command value v * d On the other hand, the d-axis voltage command value v * d The value can also be compared with the d-axis current command value i * d If the value of is set to 0, it is correspondingly set to 0.

[0123] On the other hand, the voltage command generating unit 340 may further include a limiter (not shown) for limiting the d-axis and q-axis voltage command values v * d 、v * q level to prevent the d-axis and q-axis voltage command values v * d 、v * q Exceeds the allowed range.

[0124] On the other hand, the generated d-axis and q-axis voltage command values v * d 、v * q The data is input to the axis conversion unit 350 .

[0125] The axis conversion unit 350 receives the position calculated in the speed calculation unit 320. and d-axis and q-axis voltage command values v * d 、v * q And perform axis transformation.

[0126] First, the axis conversion unit 350 performs a conversion from the two-phase rotating coordinate system to the two-phase stationary coordinate system. At this time, the position calculated by the speed calculation unit 320 can be used.

[0127] Furthermore, the axis conversion unit 350 performs conversion from the two-phase stationary coordinate system to the three-phase stationary coordinate system. Through such conversion, the axis conversion unit 350 outputs the three-phase output voltage command value v * a、v * b、v * c.

[0128] The switch control signal output unit 360 is based on the three-phase output voltage command value v * a、v * b、v * c. Generate and output the inverter switch control signal Sic based on the pulse width modulation (PWM) method.

[0129] The output inverter switching control signal Sic can be converted into a gate drive signal in a gate drive unit (not shown) and input to the gate of each switching element in the inverter 220. As a result, each switching element Sa, S'a, Sb, S'b, Sc, and S'c in the inverter 220 performs a switching operation.

[0130] Figure 5 This is an example of a motor drive device.

[0131] With reference to the accompanying drawings, Figure 5 The motor drive device 92 may include: a rectifier 98 for rectifying the three-phase AC voltage; an inductor Lx for reducing harmonics; a capacitor Cx; and an inverter 220x connected to both ends of the capacitor Cx, using the voltage across the capacitor Cx to output an AC voltage to the motor 250x.

[0132] The international surge protection standard IEC 61000 sets standards for reducing harmonics. Figure 5 The motor drive device 92 uses a reactor Lx for reducing harmonics.

[0133] especially, Figure 5 The motor drive device 92 may control the inverter 220x by detecting the voltage across the reactor Lx to reduce harmonics generated by the input current.

[0134] However, this method has the disadvantage of increasing harmonics in the inverter 220x, and also has the problem of increasing manufacturing costs because an additional reactor Lx is required.

[0135] In order to solve this problem, the present invention proposes a solution to effectively reduce the output harmonics of the inverter. Figure 7 The following explains.

[0136] Figures 6a to 6d It is explaining Figure 3 Refer to the figure when using the motor drive device.

[0137] first, Figure 6a The DC terminal voltage Vdc is shown as an example when no boost converter is included in the converter 210 and a low-capacity DC terminal capacitor C is connected to the rectifier.

[0138] In the case of using a low-capacity dc terminal capacitor C, as shown in the figure, the low-capacity dc terminal capacitor C cannot smooth the dc terminal voltage Vdc, and thus the pulsating dc terminal voltage Vdc is directly supplied to the inverter 220 .

[0139] In this case, an average voltage is formed in a voltage of about 0.7VL1 which is smaller than a peak value VL1 of the pulsating dc terminal voltage Vdc.

[0140] The inverter 220 can generate a three-phase AC voltage using a voltage of approximately 0.7VL1. However, it is difficult to smoothly drive the motor in a range below the voltage of approximately 0.7VL1, thus reducing the voltage utilization rate.

[0141] In addition, referring to the drawing, when the frequency of the input voltage is approximately 60 Hz, a voltage fluctuation of approximately 120 Hz, which is twice the frequency, occurs.

[0142] On the other hand, when using Figure 6a When the pulsating voltage is used to drive the motor 250 through the inverter 220, as shown in FIG. Figure 6b As shown in FIG. 1 , a torque ripple corresponding to ΔT1 is generated. Such a torque ripple generates vibration and noise.

[0143] On the other hand, as the capacitance of the low-capacity dc terminal capacitor C becomes smaller, current control and the like are not performed, and thus a low input power factor characteristic occurs.

[0144] In order to solve such a problem, the present invention uses a three-phase input voltage as the input voltage. Compared with a single-phase input voltage, the actual voltage utilization rate is improved by using a higher voltage.

[0145] Alternatively, in order to solve such a problem, a boost converter may be arranged within converter 210 after the rectifier unit.

[0146] Figure 6c The DC terminal voltage Vdc in the case of using a boost converter and a low-capacity DC terminal capacitor C is exemplified.

[0147] If the voltage is increased by VL2 using a boost converter, a pulsating voltage with a minimum voltage of VL2 and a peak value of VL2 + VL1 is output to the DC terminal. This results in an average voltage of approximately VL1.

[0148] Inverter 220 can generate a three-phase AC voltage using approximately VL1 voltage, and can smoothly drive the motor in most voltage ranges, thereby increasing voltage utilization and expanding the operating range.

[0149] On the other hand, Figure 6cAs shown, when the motor 250 is driven by the inverter 220 using the DC terminal voltage Vdc in the case of using a boost converter and a low-capacity DC terminal capacitor C, as shown in FIG. Figure 6d As shown in FIG, a torque fluctuation corresponding to ΔT2 is generated. That is, a torque fluctuation less than ΔT2 may be generated. Figure 6a That is, the torque fluctuation is greatly reduced.

[0150] On the other hand, if a boost converter is used, the input current Is is controlled to improve the input power factor.

[0151] Figure 7 FIG. 1 is an example of a circuit diagram of a motor drive device according to an embodiment of the present invention. Figures 8 to 15 It is explaining Figure 7 Refer to the figure when using .

[0152] The motor drive device 700 of an embodiment of the present invention includes: a rectifier unit 510, which rectifies the three-phase AC voltage 201; a DC-end capacitor C, which stores the pulsating voltage Vdc from the rectifier unit 510; a harmonic reduction unit 520, which is arranged between the rectifier unit 510 and the DC-end capacitor C, has at least one switching element, and performs harmonic reduction of the three-phase AC voltage 201; and an inverter 220, which has a plurality of switching elements and uses the voltage across the DC-end capacitor C to output the converted AC voltage to the motor.

[0153] On the other hand, when the capacitance of the DC-side capacitor C is small and the voltage across the DC-side capacitor C is pulsating, the output harmonics of the inverter 220 can be effectively reduced by using the harmonic reduction unit 520 .

[0154] On the other hand, the harmonic reduction unit 520 is turned on or off based on the output power GRb of the inverter 220. This can reduce the harmonics of the input current based on the three-phase AC voltage.

[0155] On the other hand, the motor driving device 700 according to the embodiment of the present invention further includes: a DC terminal voltage detection unit B for detecting the pulsating voltage Vdc stored in the DC terminal capacitor C; and a control unit 230 for controlling the operation of the harmonic reduction unit 520 .

[0156] On the other hand, control unit 230 can control the switching of switching elements S1 and S2 within harmonic reduction unit 520 based on the 6th or 12th harmonic components of pulsating voltage Vdc. This effectively reduces harmonics of specific frequencies in input three-phase AC voltage 201. Furthermore, harmonic distortion of the current flowing through the inverter can be reduced.

[0157] On the other hand, the control unit 230 can generate a current command based on the 6th or 12th harmonic component of the pulsating voltage Vdc, and can control the operation of the harmonic reduction unit 520 based on the generated current command. In this way, the harmonics of the specific frequency of the input three-phase AC voltage 201 can be effectively reduced.

[0158] On the other hand, the control unit 230 can control the switching elements S1 and S2 in the harmonic reduction unit 520 so that the on-duty ratio increases as the 6th or 12th harmonic component of the pulsating voltage Vdc increases. This effectively reduces the harmonics of a specific frequency of the input three-phase AC voltage 201.

[0159] In the figure, the rectifier 510 is shown as including full-bridge diodes Da, D'a, Db, D'b, Dc, and D'c for rectifying a three-phase AC voltage.

[0160] That is, between nodes n1 and n2 at both ends of the dc terminal, a first pair of diodes Da and D'a are connected in series, a second pair of diodes Db and D'b are connected in series, and a third pair of diodes Dc and D'c are connected in series.

[0161] On the other hand, the r-phase AC voltage among the three phases can be applied to the na node between the first pair of diodes Da and D'a, the s-phase AC voltage among the three phases can be applied to the nb node between the second pair of diodes Db and D'b, and the t-phase AC voltage among the three phases can be applied to the nc node between the third pair of diodes Dc and D'c.

[0162] In the figure, an example is shown in which an s-phase AC voltage is applied to the nb node and an input current im1 flows.

[0163] On the other hand, the harmonic reduction unit 520 may perform harmonic reduction on harmonics of the three-phase AC voltage.

[0164] On the other hand, the harmonic reduction unit 520 may include an inductor L1 connected between both ends of the DC terminal capacitor C, a first switching element S1, a second capacitor C1, and a second switching element S2 connected between the inductor L1 and the first switching element S1 and between the second capacitor C1 and the DC terminal capacitor C.

[0165] That is, in the harmonic reduction unit 520 , the inductor L1 and the second switching element S2 may be connected between both ends of the dc terminal capacitor C, and the first switching element S1 and the second capacitor C1 may be connected between both ends of the second switching element S2 .

[0166] Specifically, one end of the inductor L1 is connected to a node n1 that is one end of the DC terminal capacitor C, and one end of the first switching element S1 is connected to a node n3 that is the other end of the inductor L1.

[0167] The second capacitor C1 is connected between the n4 node which is the other end of the first switching element S1 and the n2 node which is the other end of the dc terminal capacitor C.

[0168] The second switching element S2 is connected between a node n3 that is the other end of the inductor L1 and a node n2 that is the other end of the dc terminal capacitor C.

[0169] On the other hand, the motor drive device 700 of the embodiment of the present invention may further include: a voltage detection unit F, detecting the voltage Vc1 as the voltage across the second capacitor C1 in the harmonic reduction unit 520; and a current detection unit G, detecting the current im2 flowing in the inductor L1 in the harmonic reduction unit 520.

[0170] On the other hand, the motor driving device 700 according to the embodiment of the present invention may further include an inverter current detecting unit M for detecting an inverter current im3 flowing between the DC terminal capacitor C and the inverter 220 .

[0171] On the other hand, the operation of the first switching element S1 or the second switching element S2 can be controlled by the switch control signal Scc from the control unit 230 .

[0172] According to the international surge protection standard IEC 61000, there are THD (Total Harmonic Distortion) (1st to 40th order) and PWHD (Partial Weighted Harmonic Distortion) (14th to 40th order). The present invention proposes a solution to reduce harmonics below the 40th order.

[0173] That is, a solution to reduce total harmonic distortion (THD) and partially weighted harmonic distortion (PWHD) is proposed. Figure 12a or Figure 12b Let's explain in further detail.

[0174] Figure 8 This is a diagram to be referred to when explaining the operation of the harmonic reduction unit based on the output power of the inverter.

[0175] With reference to the accompanying drawings, Figure 8 (a) is an example of the ripple voltage GRa of the dc terminal capacitor C. Figure 8 (b) is an example of the output power GRb of the inverter 220. Figure 8(c) may be an example of the conduction signal GRc of the harmonic reduction unit 520. Figure 8 (d) may be an example of the current GRd flowing through the inductor L1 in the harmonic reduction unit 520 .

[0176] Referring to the drawing, harmonic reduction unit 520 is turned on or off based on output power GRb of inverter 220 .

[0177] That is, the control unit 230 may control on / off based on the output power GRb of the inverter 220 .

[0178] For example, the control part 230 may calculate the output power of the inverter 220 based on the pulsating voltage Vdc of the DC terminal capacitor C detected in the DC terminal voltage detection part B, and may control on or off based on the output power of the inverter 220 .

[0179] As another example, the control unit 230 can calculate the output power of the inverter 220 based on the pulsating voltage Vdc of the DC-end capacitor C detected in the DC-end voltage detection unit B and the inverter current im3 detected in the inverter current detection unit M, and can control conduction or disconnection based on the output power of the inverter 220.

[0180] On the other hand, the harmonic reduction unit 520 may be turned on based on an increase in the output power GRb of the inverter 220 .

[0181] For example, when the output power GRb of the inverter 220 increases from time Ta1, the control unit 230 can control the harmonic reduction unit 520 to be turned on from time Ta1 to time Ta2. This allows the switching elements S1 and S2 in the harmonic reduction unit 520 to perform switching operations.

[0182] On the other hand, the harmonic reduction unit 520 may be turned off based on the increase and decrease of the output power GRb of the inverter 220 .

[0183] For example, if the output power GRb of the inverter 220 increases from time Ta1 to time Tk and then decreases from time Tk, the control unit 230 can control the harmonic reduction unit 520 to be turned off from time Ta2 to time Ta3. This allows both switching elements S1 and S2 in the harmonic reduction unit 520 to be turned off.

[0184] On the other hand, the harmonic reduction unit 520 may be turned on based on the decrease and increase of the output power GRb of the inverter 220 .

[0185] For example, if the output power GRb of the inverter 220 decreases from time Tk to time Tm and increases from time Tm, the control unit 230 can control the harmonic reduction unit 520 to be turned on from time Ta3 to time Ta4. This allows the switching elements S1 and S2 in the harmonic reduction unit 520 to perform switching operations.

[0186] On the other hand, the control unit 230 can control the harmonic reduction unit 520 to be turned off during the period from time Ta4 to time Ta5 based on the increase in output power GRb of the inverter 220 and the decrease from time To. As a result, both switching elements S1 and S2 in the harmonic reduction unit 520 can be turned off.

[0187] On the other hand, the control unit 230 can control the harmonic reduction unit 520 to be turned on from time Ta5 based on the decrease in output power GRb of the inverter 220 and the increase from time Tp. This allows the switching elements S1 and S2 in the harmonic reduction unit 520 to perform switching operations.

[0188] Specifically, harmonic reduction unit 520 can be turned on during a first period Ta1-Ta2 based on an increase in output power GRb of inverter 220, turned off during a second period Ta2-Ta3 based on an increase or decrease in output power GRb of inverter 220, and turned on during a third period Ta4-Ta5 based on a decrease or increase in output power GRb of inverter 220. This reduces the harmonics of input three-phase AC voltage 201 and the harmonic distortion of the current input to inverter 220.

[0189] On the other hand, the ripple voltage Vdc stored in the capacitor C may be smaller when the harmonic reduction unit 520 is turned off than when the harmonic reduction unit 520 is turned on.

[0190] The figure illustrates that the level of ripple voltage Vdc during the periods Ta1 to Ta2, Ta3 to Ta4, and after Ta5, when harmonic reduction unit 520 is on, is higher than the level of ripple voltage Vdc during the periods Ta2 to Ta3, and Ta4 to Ta5, when harmonic reduction unit 520 is off. This reduces harmonics in the input current based on the three-phase AC voltage.

[0191] Figures 9a to 9d It is a diagram illustrating various operations of the harmonic reduction unit 520 when it is turned on.

[0192] Figure 9a The example in which the first switching element S1 is turned off and the second switching element S2 is turned on in the harmonic reduction unit 520 is shown. This illustrates a first current path a flowing through the inductor L1 and the second switching element S2.

[0193] Figure 9b The example in which the first switching element S1 is turned on and the second switching element S2 is turned off in the harmonic reduction unit 520 is shown. This illustrates the second current path b flowing through the inductor L1, the first switching element S1, and the second capacitor C1.

[0194] Figure 9c The example in which the first switching element S1 is turned on and the second switching element S2 is turned off in the harmonic reduction unit 520 is shown. This illustrates a third current path pathc flowing through the first switching element S1, the inductor L1, and the DC terminal capacitor C.

[0195] Figure 9d The example in which the first switching element S1 is turned off and the second switching element S2 is turned on in the harmonic reduction unit 520 is shown. This illustrates a fourth current path d flowing through the inductor L1 and the DC-side capacitor C.

[0196] On the other hand, according to Figures 9a to 9d When the harmonic reduction unit 520 is turned on, the first switching element S1 and the second switching element S2 can operate complementarily.

[0197] That is, when the harmonic reduction unit 520 is turned on, only one of the first switching element S1 and the second switching element S2 may be turned on, and the other switching element may be turned off.

[0198] Figure 10a Example input to Figure 7 The waveform of the input current im1 of the rectifier 510. The input current im1 may contain all harmonic components.

[0199] Right now, Figure 10a The waveform of the input current im1 may be a waveform corresponding to the disconnection of the harmonic reduction unit 520 .

[0200] then, Figure 10b The waveform of the current im2 flowing through the inductor L1 when the harmonic reduction unit 520 is turned on is shown as an example. The current im2 flowing through the inductor L1 may be a compensation current waveform for reducing the 1st to 40th harmonics among the harmonic components.

[0201] then, Figure 10c This example shows that the harmonic reduction unit 520 is turned on. Figure 10a The waveform of the input current im1 is compensated by the waveform of the current im2 flowing through the inductor L1 , thereby reducing the harmonics of the 1st to 40th harmonics of the waveform of the input current imc1 .

[0202] As described above, since the harmonics in the input current based on the three-phase AC voltage are reduced, the control stability is improved when the motor drive device is operating.

[0203] Figure 11 yes Figure 3 An example of an internal block diagram of the control unit.

[0204] 1 , the control unit 230 may include an input current command generating unit 720 , a power command generating unit 730 , a conversion unit 725 , and a voltage command generating unit 740 .

[0205] The control part 230 may filter or extract the 40th order and lower harmonic components of the pulsating voltage and control the harmonic reduction part 520 based on the extracted harmonic current.

[0206] The input current command generating unit 720 can extract the 40th order or lower harmonic current I from the input current Is based on the three-phase AC voltage 201. * s.

[0207] The conversion unit 725 may perform axis conversion on the three-phase AC voltage Vs based on the rotating coordinate system. The converted three-phase AC voltage may be input to the power command generation unit 730.

[0208] The power command generating unit 730 may include a harmonic current I extracted from the input current command generating unit 720. * The multiplier 731 multiplies s by the three-phase AC voltage component output from the conversion unit 725.

[0209] Thus, the power command generating unit 730 can generate the power command based on the harmonic current I * s to generate the power command value P * .

[0210] The voltage command generating unit 740 can generate a voltage command based on the power command value P * To generate the compensation voltage command value V * .

[0211] In particular, the voltage command generating unit 740 may generate a voltage command based on the power command value P * and harmonic currents below 40th order I * s to generate the compensation voltage command value V * .

[0212] The control unit 230 can be based on the compensation voltage command value V * To control the operation of the first switching element S1 or the second switching element S2 in the harmonic reduction unit 520.

[0213] Alternatively, the control unit 230 may be configured to compensate for the voltage command value V * To control the operation of the upper arm switching elements Sa, Sb, Sc and the lower arm switching elements S′a, S′b, S′c in the inverter 220 .

[0214] Figure 12a yes Figure 7 An example of an internal block diagram of the control unit.

[0215] 1 , the control unit 230a1 may include: a first filter 1204 for filtering a DC component of the pulsating voltage Vdc; and a second filter 1206 for filtering a 6th or 12th harmonic component of the pulsating voltage Vdc.

[0216] On the other hand, the control unit 230a1 may further include a compensation current generator 1220 that generates a compensation current based on the DC component or fundamental (1st) component of the pulsating voltage Vdc from the first filter 1204 and the 6th or 12th harmonic component of the pulsating voltage Vdc.

[0217] For example, the compensation current generator 1220 can generate a compensation current of the 5th or 7th harmonic of the input current corresponding to the 6th harmonic of the pulsating voltage Vdc, or can generate a compensation current of the 11th or 13th harmonic of the input current corresponding to the 12th harmonic of the pulsating voltage Vdc.

[0218] On the other hand, the control part 230 a 1 may further include a compensation current controller 1230 that performs compensation current control based on the compensation current generated in the compensation current generator 1220 .

[0219] For example, the compensation current controller 1230 may control the operation of the switching elements S1 and S2 in the harmonic reduction unit 520 in the converter 210 .

[0220] Specifically, the compensation current controller 1230 can control the on-duty ratio of the switching elements S1 and S2 in the harmonic reduction unit 520 to increase as the 6th or 12th harmonic component of the pulsating voltage Vdc increases. This effectively reduces harmonics of a specific order in the input current based on the three-phase AC voltage.

[0221] Figure 12b yes Figure 7 Another example of the internal block diagram of the control unit.

[0222] Referring to the accompanying drawings, the control unit 230a2 may include: a first filter 1204 for filtering the DC component of the pulsating voltage Vdc; a second filter 1206 for filtering the 6th or 12th harmonic components of the pulsating voltage Vdc; and a third filter 1202 for filtering the 40th and lower harmonic components of the pulsating voltage Vdc.

[0223] and Figure 12a Unlike the control unit 230a1, the control unit 230a2 may further include a third filter 1202. Thus, the 40th-order and lower harmonic components of the pulsating voltage Vdc can be further compensated.

[0224] On the other hand, the control unit 230a2 may further include a compensation current generator 1220 that generates a compensation current based on the DC component or fundamental (1st) component of the pulsating voltage Vdc from the first filter 1204 and the 6th or 12th harmonic component of the pulsating voltage Vdc.

[0225] On the other hand, the compensation current generator 1220 may also generate the compensation current based on the DC component or fundamental (1st) component of the pulsating voltage Vdc from the first filter 1204 and the 40th and lower harmonic components of the pulsating voltage Vdc.

[0226] On the other hand, the control part 230 a 2 may further include a compensation current controller 1230 that performs compensation current control based on the compensation current generated in the compensation current generator 1220 .

[0227] For example, the compensation current controller 1230 may control the operation of the switching elements S1 and S2 in the harmonic reduction unit 520 in the converter 210 .

[0228] Figure 13a This is a diagram illustrating the reduction of harmonics by the operation of the harmonic reduction unit 520 and the inverter 220 .

[0229] Referring to the drawings, the control unit 230 according to the embodiment of the present invention may output a switch control signal Scc to the harmonic reduction unit 520 and may output an inverter switch control signal Sic to the inverter 220 .

[0230] In particular, the control unit 230 may control the operation of the harmonic reduction unit 520 based on the switch control signal Scc to reduce harmonics below the 40th order and the 6th or 12th order harmonic components of the pulsating voltage Vdc.

[0231] On the other hand, the control unit 230 may control the operation of the inverter 220 based on the inverter switching control signal Sic to reduce harmonics of the 40th order and below.

[0232] Figure 13b The case where compensation is performed on the 40th-order harmonics and lower harmonics of the pulsating voltage Vdc and the case where compensation is performed on the 6th-order harmonics of the pulsating voltage Vdc are exemplified.

[0233] Referring to the drawings, the horizontal axis may represent the order of harmonics, and the vertical axis may represent the ratio of the fundamental wave to the harmonics.

[0234] That is, when the control unit 230a2 compensates for the 40th-order harmonics and below, it can be confirmed that the 10th-order to 40th-order harmonics are significantly reduced.

[0235] On the other hand, when the control unit 230a2 compensates for the 40th-order and lower harmonics, a considerable portion of the 10th-order and lower harmonic components remains.

[0236] therefore, Figure 12a The control unit 230a1 or Figure 12b The control unit 230a2 can perform compensation for the 6th harmonic of the pulsating voltage Vdc.

[0237] Thus, when the sixth harmonic of the pulsating voltage Vdc is compensated, it can be confirmed that the sixth harmonic component is significantly reduced.

[0238] As a result, the fifth harmonic or seventh harmonic of the input current corresponding to the sixth harmonic of the pulsating voltage Vdc can be significantly reduced.

[0239] Similarly, in Figure 12a The control unit 230a1 or Figure 12b When the control unit 230a2 compensates for the 12th harmonic of the pulsating voltage Vdc, the 11th harmonic or the 13th harmonic of the input current can be significantly reduced.

[0240] Figure 14 This is a diagram to be referred to when explaining the output power of the inverter and the operation of the load.

[0241] Referring to the accompanying drawings, Figure 14 As shown in (a), as the output power or load (Load) of the inverter increases, the level of the ripple voltage Vdc stored in the dc-side capacitor C increases.

[0242] Therefore, if Figure 14 As shown in (b), as the output power or load of the inverter increases, the harmonics of the input current based on the three-phase AC voltage 201 increase.

[0243] Therefore, if Figure 14 As shown in (c), the control unit 230 of the embodiment of the present invention can control the on-duty ratio of the switching elements S1 and S2 in the harmonic reduction unit 520 to increase as the harmonics of the input current based on the three-phase AC voltage 201 increase.

[0244] In particular, control unit 230 can control the on-duty ratio of switching elements S1 and S2 within harmonic reduction unit 520 to increase as the 6th or 12th harmonic component of pulsating voltage Vdc increases. This effectively reduces harmonics of specific orders in the input current based on the three-phase AC voltage.

[0245] Figure 15 An example of a circuit board arrangement of a motor drive device according to an embodiment of the present invention is shown.

[0246] Referring to the drawings, the three-phase AC voltage 201 may be input to the inverter circuit board 1620 equipped with the inverter 220 and the DC terminal voltage detection unit B through the filter circuit board 1605 equipped with a noise filter and the like.

[0247] On the other hand, the inverter circuit board 1620 may also include Figure 7 The rectifier unit 510, the DC terminal capacitor C, etc.

[0248] On the other hand, the main circuit board 1610 may include a voltage step-down unit 1615 that outputs a voltage of 15 V based on a voltage of 220 V as an example of a single-phase voltage from the filter circuit board 1605 or the like.

[0249] On the other hand, the main circuit board 1610 can output a voltage of 15V, a voltage of 220V, etc. to the inverter circuit board 1620.

[0250] On the other hand, the main circuit board 1610 can communicate with the inverter circuit board 1620 and the fan circuit board 1640 through a plurality of communication terminals TEa and TEb.

[0251] On the other hand, the inverter circuit board 1620 can drive the compressor motor 250, and the fan circuit board 1640 can drive the fan motors FMa and FMb.

[0252] On the other hand, the inverter circuit board 1620 can communicate with the main circuit board 1610 through a plurality of communication terminals TEc and TEd.

[0253] On the other hand, the inverter circuit board 1620 can communicate with the harmonic reduction circuit board 1630 through a plurality of communication terminals TE1 and TE2.

[0254] On the other hand, the harmonic reduction circuit board 1630 can communicate with the inverter circuit board 1620 through a plurality of communication terminals TE3 and TE4.

[0255] On the other hand, the harmonic reduction circuit board 1630 may include Figure 7 The harmonic reduction unit 520, the current detection unit G, the second voltage detection unit F and the control unit 230 are provided.

[0256] On the other hand, the control part 230 may receive information on the ripple voltage Vdc from the DC terminal voltage detection part B through the communication lines CBc and CBd between the inverter circuit board 1620 and the harmonic reduction circuit board 1630 .

[0257] On the other hand, the control unit 230 may control the harmonic reduction unit 520 based on the pulsating voltage Vdc from the dc terminal voltage detection unit B.

[0258] On the other hand, the control unit 230 can receive information about the pulsating voltage Vdc from the DC terminal voltage detection unit B and information about the inverter current im3 from the inverter current detection unit M through the communication lines CBc and CBd between the inverter circuit board 1620 and the harmonic reduction circuit board 1630.

[0259] Furthermore, the control unit 230 may control the harmonic reduction unit 520 based on the information on the ripple voltage Vdc from the dc terminal voltage detection unit B and the information on the inverter current im3 from the inverter current detection unit M.

[0260] Specifically, the control unit 230 can calculate the output power of the inverter 220 based on the information about the ripple voltage Vdc from the DC terminal voltage detection unit B and the information about the inverter current im3 from the inverter current detection unit M, and can turn on or off the harmonic reduction unit 520 based on the output power of the inverter 220. In this way, the harmonics of the input current based on the three-phase AC voltage can be reduced.

[0261] Figure 16 This is an example of a circuit diagram of a motor drive device according to another embodiment of the present invention.

[0262] Referring to the accompanying drawings, a motor driving device 700b according to another embodiment of the present invention is Figure 7 Similar, but different in that Figure 7 The control unit 230 is divided into two control units.

[0263] That is, the motor driving device 700 b according to another embodiment of the present invention may include the control unit 230 for controlling the harmonic reduction unit 520 and the inverter control unit 230 b for controlling the inverter 220 .

[0264] Therefore, if Figure 4 As shown in the internal block diagram of , the inverter control unit 230 b may include an axis conversion unit 310 , a speed calculation unit 320 , 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 .

[0265] on the other hand, Figure 16 The control unit 230 can execute the Figures 8 to 14 The actions of the control unit described in .

[0266] On the other hand, Figure 15 In related terms, the control unit 230 for controlling the harmonic reduction unit 520 may be configured on the harmonic reduction circuit board 1630 , and the inverter control unit 230 b may be configured on the inverter circuit board 1620 .

[0267] On the other hand, the control unit 230 in the harmonic reduction circuit board 1630 can communicate with the inverter control unit 230 b in the inverter circuit board 1620 through the plurality of communication terminals TE3 and TE4.

[0268] For example, the control section 230 in the harmonic reduction circuit board 1630 may receive information on the pulsating voltage Vdc from the inverter control section 230 b in the inverter circuit board 1620 through the communication lines CBc and CBd.

[0269] On the other hand, the control unit 230 may control the harmonic reduction unit 520 based on the pulsating voltage Vdc from the dc terminal voltage detection unit B.

[0270] On the other hand, the control unit 230 in the harmonic reduction circuit board 1630 can receive information about the pulsating voltage Vdc from the inverter control unit 230b in the inverter circuit board 1620 and information about the inverter current im3 from the inverter current detection unit M through the communication lines CBc and CBd.

[0271] Furthermore, the control unit 230 can control the harmonic reduction unit 520 based on the information on the ripple voltage Vdc from the DC terminal voltage detection unit B and the information on the inverter current im3 from the inverter current detection unit M. This can reduce the harmonics of the input current based on the three-phase AC voltage.

[0272] Figure 17 FIG. 1 is an example of a circuit diagram of a motor drive device according to another embodiment of the present invention. Figure 18 It is explaining Figure 17 Refer to the figure when using .

[0273] A motor drive device 700c according to another embodiment of the present invention includes: a rectifier 510 for rectifying a three-phase AC voltage 201; a DC-terminal capacitor C for storing a pulsating voltage Vdc from the rectifier 510; a first voltage detector B for detecting the pulsating voltage Vdc stored in the DC-terminal capacitor C; a harmonic reduction unit 520 disposed between the rectifier 510 and the DC-terminal capacitor C, comprising at least one switching element and a second capacitor C1, for reducing harmonics of the three-phase AC voltage 201; and a current detector G for detecting a current flowing in the DC-terminal capacitor C. A current im2 flowing in the harmonic reduction unit 520; a second voltage detection unit F, detecting a voltage Vc1 across the second capacitor C1 in the harmonic reduction unit 520; an inverter 220, having a plurality of switching elements, using the voltage across the DC-terminal capacitor C to output a converted AC voltage to the motor; and a control unit 230, controlling the harmonic reduction unit 520 based on the pulsating voltage Vdc from the first voltage detection unit B, the detected current im2 from the current detection unit G, and the detected voltage from the second voltage detection unit F.

[0274] On the other hand, when the capacitance of the DC-side capacitor C is small and the voltage across the DC-side capacitor C is pulsating, the output harmonics of the inverter 220 can be effectively reduced by using the harmonic reduction unit 520 .

[0275] In particular, the motor driving device 700 c according to another embodiment of the present invention can reduce harmonics based on the three-phase AC voltage 201 without having an input current detection unit for detecting input current when the three-phase AC voltage 201 is input.

[0276] In the figure, the rectifier 510 is shown as including full-bridge diodes Da, D'a, Db, D'b, Dc, and D'c for rectifying a three-phase AC voltage.

[0277] On the other hand, the harmonic reduction unit 520 may include an inductor L1 connected between both ends of the DC terminal capacitor C, a first switching element S1, a second capacitor C1, and a second switching element S2 connected between the inductor L1 and the first switching element S1 and between the second capacitor C1 and the DC terminal capacitor C.

[0278] On the other hand, the inverter control unit 230b can control the output current i flowing between the inverter 220 and the motor 250 based on the output current i detected by the output current detection unit E. o To control the switching elements in the inverter 220.

[0279] In particular, the inverter control unit 230b can be based on the output current i from the output current detection unit E. o The inverter 220 outputs an inverter switching control signal Sic for controlling the switching elements in the inverter 220.

[0280] Figure 18 An example of a circuit board arrangement of a motor drive device according to still another embodiment of the present invention is shown.

[0281] Referring to the drawings, the three-phase AC voltage 201 may be input to the inverter circuit board 1620 equipped with the inverter 220 and the like through a filter circuit board 1605 equipped with a noise filter and the like.

[0282] On the other hand, the inverter circuit board 1620 may also include Figure 17 The rectifier unit 510, the DC terminal capacitor C, etc.

[0283] On the other hand, the main circuit board 1610 may include a voltage step-down unit 1615 that outputs a voltage of 15 V based on a voltage of 220 V as an example of a single-phase voltage from the filter circuit board 1605 or the like.

[0284] On the other hand, the main circuit board 1610 can output a voltage of 15V, a voltage of 220V, etc. to the inverter circuit board 1620.

[0285] On the other hand, the main circuit board 1610 can communicate with the inverter circuit board 1620 and the fan circuit board 1640 through a plurality of communication terminals TEa and TEb.

[0286] On the other hand, the inverter circuit board 1620 can drive the compressor motor 250, and the fan circuit board 1640 can drive the fan motors FMa and FMb.

[0287] On the other hand, the inverter circuit board 1620 can communicate with the main circuit board 1610 through a plurality of communication terminals TEc and TEd.

[0288] On the other hand, no additional communication line may be configured between the inverter circuit board 1620 and the harmonic reduction circuit board 1630 .

[0289] This allows the harmonic reduction circuit board 1630 to operate independently, and reduces manufacturing costs.

[0290] On the other hand, the harmonic reduction unit 520, the current detection unit G, the first voltage detection unit B, the second voltage detection unit F, and the control unit 230 can be arranged on the first circuit board 1630, and the inverter 220 can be arranged on the second circuit board 1620 separate from the first circuit board 1630. As described above, by arranging the inverter 220 and the harmonic reduction unit 520 on separate circuit boards, the harmonic reduction unit 520 can be effectively operated.

[0291] In this case, the first circuit board 1630 may be a harmonic reduction circuit board 1630 , and the second circuit board 1620 may be an inverter circuit board 1620 .

[0292] On the other hand, a rectifier 510 and a DC-terminal capacitor C may also be configured on the second circuit board 1620 .

[0293] Figure 19 This is an example of a circuit diagram of a motor drive device according to another embodiment of the present invention.

[0294] Referring to the accompanying drawings, a motor driving device 700cb according to another embodiment of the present invention is Figure 17 The present invention is similar to the present invention, but differs in that a second current detecting unit M is further included to detect a second current im3 flowing between the dc terminal capacitor C and the inverter 220.

[0295] The second current im3 at this time can also be called a DC terminal current.

[0296] On the other hand, the control unit 230 can control the harmonic reduction unit 520 based on the pulsating voltage Vdc from the first voltage detection unit B, the detected current im2 from the current detection unit G, the detected voltage Vc1 from the second voltage detection unit F, and the second current im3 from the second current detection unit M. In this way, harmonics can be reduced without detecting the input current when the three-phase AC voltage 201 is input.

[0297] On the other hand, the harmonic reduction unit 520, the current detection unit G, the first voltage detection unit B, the second current detection unit M, the second voltage detection unit F, and the control unit 230 can be arranged on the first circuit board 1630, and the inverter 220 can be arranged on the second circuit board 1620 separate from the first circuit board 1630. This allows the harmonic reduction unit 520 to operate efficiently.

[0298] On the other hand, the control section 230 may control the harmonic reduction section 520 based on the information on the ripple voltage Vdc from the dc terminal voltage detection section B and the information on the inverter current im3 from the inverter current detection section M.

[0299] Specifically, the control unit 230 can calculate the output power of the inverter 220 based on the information about the ripple voltage Vdc from the DC terminal voltage detection unit B and the information about the inverter current im3 from the inverter current detection unit M, and can turn on or off the harmonic reduction unit 520 based on the output power of the inverter 220. In this way, the harmonics of the input current based on the three-phase AC voltage can be reduced.

[0300] Figure 20 This is an example of a circuit diagram of a motor drive device according to another embodiment of the present invention.

[0301] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the specific embodiments described above. A person skilled in the art can perform various modified implementations thereof without departing from the technical idea of the present invention for protection in the scope of the rights. Such modified implementations should not be understood separately from the technical idea or prospects of the present invention.

Claims

1. A motor drive device, wherein: include: The rectifier unit rectifies the three-phase AC voltage; a capacitor for storing the pulsating voltage from the rectifying unit; a harmonic reduction unit, disposed between the rectifier unit and the capacitor, having at least one switching element and performing harmonic reduction of the three-phase AC voltage; as well as an inverter having a plurality of switching elements and outputting a converted AC voltage to a motor using the voltage across the capacitor; The harmonic reduction unit is turned on or off based on output power of the inverter.

2. The motor drive device according to claim 1, wherein: The harmonic reduction portion is turned off based on an increase and a decrease in output power of the inverter, and is turned on based on a decrease and an increase in output power of the inverter.

3. The motor drive device according to claim 1, wherein: The harmonic reduction unit is turned on based on an increase in output power of the inverter.

4. The motor drive device according to claim 1, wherein: The harmonic reduction unit is turned on during a first period based on an increase in output power of the inverter; The harmonic reduction unit is turned off during a second period based on an increase and a decrease in output power of the inverter; The harmonic reduction unit is turned on during a third period based on a decrease and an increase in output power of the inverter.

5. The motor drive device according to claim 1, wherein: The ripple voltage stored in the capacitor is smaller when the harmonic reduction unit is off than when the harmonic reduction unit is on.

6. The motor drive device according to claim 1, wherein: Also includes: a voltage detection unit that detects the pulsating voltage stored in the capacitor; and a control unit for controlling the operation of the harmonic reduction unit; The control unit controls switching of the switching element in the harmonic reduction unit based on a sixth-order or twelfth-order harmonic component of the pulsating voltage.

7. The motor drive device according to claim 6, wherein: The control unit generates a current command based on the sixth or twelfth harmonic component of the pulsating voltage, and controls an operation of the harmonic reduction unit based on the generated current command.

8. The motor drive device according to claim 6, wherein: The control unit controls the switching element in the harmonic reduction unit to increase an on-duty ratio as a sixth-order or twelfth-order harmonic component of the pulsating voltage increases.

9. A motor drive device, wherein: include: The rectifier unit rectifies the three-phase AC voltage; a capacitor for storing the pulsating voltage from the rectifying unit; a harmonic reduction unit, disposed between the rectifier unit and the capacitor, having at least one switching element and performing harmonic reduction of the three-phase AC voltage; an inverter having a plurality of switching elements and outputting a converted AC voltage to a motor using the voltage across the capacitor; a voltage detection unit for detecting the pulsating voltage stored in the capacitor; as well as a control unit for controlling the operation of the harmonic reduction unit; The control unit controls switching of the switching element based on a sixth or twelfth harmonic component of the pulsating voltage.

10. An air conditioner, characterized in that: including a motor drive unit, The motor drive device comprises: The rectifier unit rectifies the three-phase AC voltage; a capacitor for storing the pulsating voltage from the rectifying unit; a harmonic reduction unit, disposed between the rectifier unit and the capacitor, having at least one switching element and performing harmonic reduction of the three-phase AC voltage; and an inverter having a plurality of switching elements and outputting a converted AC voltage to a motor using the voltage across the capacitor; The harmonic reduction unit is turned on or off based on output power of the inverter.

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