JP2008295126A - Power converter system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress conduction noise which flows out to a system power line, by reducing a common-mode current which leaks to the ground via the floating capacitor of a motor, in a power converter system equipped with an inverter device and a motor driven by the inverter device. <P>SOLUTION: Each phase of wiring which connects the input part of an inverter device in the power converter system to a system power source is connected to the radiator of the inverter device, using a grounding capacitor, and the motor connected to the output part of the inverter device is accommodated, as well as; a frame connected electrically with the radiator is connected to grounding by using an impedance element. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inverter device that converts an alternating current input from a system power source into a direct current by a semiconductor element or the like, and then converts the direct current back to an alternating current, and a power converter that includes a motor driven by an output from the inverter device. Is related to the container system.

Recent motors are rotated by receiving an output from an inverter device which is a power converter that converts alternating current from a system power source into an arbitrary frequency and an arbitrary voltage. That is, a power converter system including a power converter such as an inverter device and a motor driven by the power converter has become mainstream.
The inverter device in this power converter system includes a rectifier circuit unit that rectifies an AC power source with a diode to obtain a DC voltage, a smoothing capacitor that smoothes the output DC voltage of the rectifier circuit, and the DC voltage is converted into an AC voltage by a switching element The basic part is comprised from the inverter part converted into.

When the inverter device performs switching at a high frequency, the output terminal of the inverter unit fluctuates at a high frequency with respect to the earth ground. Due to this potential fluctuation, a high-frequency current flows through the stray capacitance of the inverter unit and the stray capacitance of the motor connected to the output terminal of the inverter unit. This high-frequency current is called a common mode current, and a part of it returns to the inverter device and the motor, but the rest of the high-frequency current goes to earth ground and becomes earth leakage current.
If conduction noise generated by this high-frequency ground leakage current flows out to the system power supply line, an electronic device that is weak against the conduction noise connected to the system power supply line may malfunction.
The common mode current that generates the conduction noise increases as the switching frequency of the inverter unit increases. Recent inverters have a higher carrier frequency to reduce noise, and conduction noise is a problem.

Conventionally, as means for solving such a problem of conduction noise, a noise filter is provided at the input end of the inverter device to prevent conduction noise from flowing out to the system power supply line.
However, this means has a problem that the noise filter is very large and expensive, and the cost of the power converter increases.

  In addition, as a means for suppressing noise generated based on the common mode current caused by potential fluctuation due to switching at high frequency of the inverter device, a radiator is separately provided in the rectifier circuit portion and the inverter portion of the inverter device, Insulate these heatsinks from the inverter case, and connect the heatsinks provided in the rectifier circuit unit and the heatsinks provided in the inverter unit to a sufficiently high impedance value such as resistance or reactor compared to normal wires. Connecting with a material (impedance element) is disclosed (for example, see Patent Document 1).

JP 2006-115649 A (page 4, FIG. 1)

  However, in a power converter configured to provide a separate radiator in the rectifier circuit section and the inverter section of the inverter device and connect these radiators with resistors or impedance elements, the common mode current flowing back to the inverter device is reduced. The radiation noise caused by this high-frequency common mode current can be suppressed, but the common mode current that leaks to the ground through the stray capacitance of the inverter and the stray capacitance of the motor cannot be suppressed. There was a problem that the conduction noise flowing out to the line could not be reduced.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is not to provide a large and expensive noise filter, but through the stray capacitance of the inverter unit and the stray capacitance of the motor, in particular, the motor. The objective is to obtain a power converter system that suppresses the high-frequency common mode current that leaks to the ground through the stray capacitance to the ground and reduces the conduction noise that flows out to the system power line.

  A power converter system according to the present invention includes an inverter device, a motor connected to the output unit of the inverter device, each phase of wiring connecting the input unit of the inverter device and the system power supply, and a radiator of the inverter device. Are connected to a grounding capacitor, a frame that houses a motor and is connected to a radiator, and an impedance element that connects the frame to a ground.

  A power converter system according to the present invention includes an inverter device, a motor connected to the output unit of the inverter device, each phase of wiring connecting the input unit of the inverter device and the system power supply, and a radiator of the inverter device. A grounding capacitor for connecting the motor, a frame for housing the motor and connected to the radiator, and an impedance element for connecting the frame to the earth ground. The high-frequency common mode current that flows in can be reduced, and the effect that conduction noise to the system power supply can be suppressed can be obtained.

Embodiment 1.
FIG. 1 is a schematic cross-sectional view of a power converter system according to Embodiment 1 of the present invention.
As shown in FIG. 1, a power converter system 100 according to the present embodiment includes a rectifier circuit unit that rectifies an AC power source with a diode on the input unit side to obtain a DC voltage, and smoothes the output DC voltage of the rectifier circuit. An inverter device 2 provided with a smoothing capacitor and an inverter unit (not shown) for converting the DC voltage into an AC voltage by a switching element on the output unit side, and a motor 3 are provided.
The input unit of the inverter device 2 is connected to an AC system power supply 1. For the wiring from the system power supply 1, a shield wire or the like is used to prevent radiation noise from the cable, and the jacket is connected to the earth ground 8. Each phase of wiring from the system power supply 1 to the input unit of the inverter device 2 and the radiator 6 of the inverter device 2 are connected by a ground capacitor 7.
A motor 3 is connected to the output unit of the inverter device 2. The motor 3 is housed in a frame 4, and the frame 4 is electrically connected directly to the radiator 6 with a cable or the like, and is connected to the earth ground 8 via an impedance element 9.

Since power converter system 100 of the present embodiment is configured as described above, the high-frequency common mode current generated by the high-frequency switching of inverter device 2 flows into motor 3 through the motor wire, and the motor 3 is transmitted to the frame 4 through the stray capacitance 5. Then, it takes a path that flows into the radiator 6 of the inverter device 2 electrically connected to the frame 4 and returns to the inverter device 2 that is the generation source via the grounding capacitor 7.
In the power converter system 100 according to the present embodiment, each phase of the wiring from the system power supply 1 to the input unit of the inverter device 2 and the radiator 6 of the inverter device 2 are connected by the grounding capacitor 7. The mode current is bypassed to the inverter device 2 side and does not flow to the system power supply 1 side.

In addition, the frame 4 housing the motor 3 and the radiator 6 electrically connected to the frame 4 are not directly connected to the earth ground 8 but are connected via the impedance element 9. Therefore, the high-frequency common mode current flowing into the system power supply 1 through the earth ground 8 can be extremely reduced.
That is, since the common mode current transmitted to the frame 4 via the stray capacitance 5 of the motor 3 hardly flows to the earth ground 8, the conduction noise from the earth earth 8 to the system power source 1 can be extremely reduced. It is possible to prevent malfunction of an electronic device that is sensitive to conduction noise connected to the power line.
In the inverter device 2 according to the present embodiment, the frequency of noise due to the high-frequency common mode current is usually in a band from about 100 kHz to about several tens of MHz. Therefore, for example, the above band is sufficient for the impedance element 9. An insulating material having a high impedance (hereinafter referred to as an insulating material element), a magnetic body, a magnetic coil, or the like is used. Examples of the insulating material element include a plastic material and a rubber material. The insulating material element is inexpensive and can reduce the cost of the power converter system.

Embodiment 2.
FIG. 2 is a schematic cross-sectional view of a power converter system according to Embodiment 2 of the present invention.
As shown in FIG. 2, the power converter system 200 according to the present embodiment includes a common mode coil 10 in each phase of wiring between an AC system power supply 1 and an input unit of an inverter device 2 that is a power converter. The power converter system is the same as that of the first embodiment except that is added.
The common mode coil 10 used in the present embodiment is a coil in which a wire of each phase is wound around the coil core in the same phase, and there is little influence on the normal current flowing in the opposite direction of each phase. For the common mode current flowing in the same direction, it acts as an inductance that generates a large impedance. When the common mode coil 10 having such an action is installed in each phase of the wiring between the AC system power supply 1 and the input unit of the inverter device 2, the common mode current flowing through the grounding capacitor 7 is increased, It is possible to further prevent conduction noise due to current from being conducted to the system power supply 1.
That is, in the power converter system 200 of the present embodiment, the frame 4 electrically connected to the radiator 6 of the inverter device 2 is connected to the earth ground 8 via the impedance element 9, and the system power source 1 Since the common mode coil 10 is additionally provided between the input unit of the inverter device 2, the conduction noise caused by the high frequency common mode current flowing on the system power supply 1 side can be further reduced.

Embodiment 3.
FIG. 3 is a schematic cross-sectional view of a power converter system according to Embodiment 3 of the present invention.
As shown in FIG. 3, the power converter system 300 according to the present embodiment includes an inductance element 11 and a resistance element 12 in parallel as impedance elements that connect the frame 4 housing the motor 3 and the earth ground 8. It is the same as that of the power converter system of Embodiment 1 except having used what was connected to. Examples of the inductance element include a magnetic coil and a bead type inductance element, and examples of the resistance element include a resistive element (bulk, bead) and the like.
The power converter system 300 of the present embodiment has the same effect as that of the power converter system of the first embodiment, and uses an impedance element in which an inductance element 11 and a resistance element 12 are connected in parallel. Therefore, the direct current component and the low frequency component generated in the frame 4 and the radiator 6 can be released to the earth ground 8, and potential generation in the frame 4 and the radiator 6 can be prevented.

In the present embodiment, an impedance element in which an inductance element 11 and a resistance element 12 are arranged in parallel is used for connection between the motor frame 4 and the earth ground 8, but the inductance element 11 and the resistance element The same effect can be obtained even if any one of 12 elements is used.
Further, as in the power converter system 400 shown in FIG. 4, three types of elements, that is, an inductance element 11, a resistance element 12, and an insulating material element 13 are connected as impedance elements that connect the frame 4 and the earth ground 8. May be used in parallel, and the same effect can be obtained.
Further, any one of the inductance element 11 and the resistance element 12 and the insulating material element 13 may be used in parallel, and the same effect can be obtained.

Embodiment 4.
FIG. 5 is a schematic cross-sectional view of a power converter system according to Embodiment 4 of the present invention.
As shown in FIG. 5, the power converter system 500 of the present embodiment is the same as the power converter system of the first embodiment except that the frame 4 housing the motor 3 is covered with an outer casing 14. It is the same.
In the present embodiment, the frame 4 is directly connected to the radiator 6 of the inverter device 2 by a cable or the like, and is connected to the outer casing 14 via the impedance element 9. Is connected to the earth ground 8. In addition to the insulating material element, an impedance element or a resistance element may be used for the impedance element 9.
In the power converter system 500 of the present embodiment, the frame 4 housing the motor 3 is covered with the outer casing 14 and connected to the outer casing 14 via the impedance element 9. Since 14 is connected to the earth ground 8, it is possible to suppress the transmission noise and also the radiation noise from the motor.

Embodiment 5. FIG.
FIG. 6 is a schematic cross-sectional view of a power converter system according to Embodiment 5 of the present invention.
As shown in FIG. 6, the power converter system 600 of the present embodiment includes an inverter device 2 including a rectifier circuit unit, a smoothing capacitor, and an inverter unit, a radiator 6, and a frame 4 that houses a motor 3. The power converter system is the same as that of the fourth embodiment except that it is covered with the outer casing 14.
In the power converter system 600 of the present embodiment, the inverter device 2, the radiator 6, and the frame 4 housing the motor 3 are housed in one outer casing 14, and the power conversion of the fourth embodiment In addition to having the same effect as the motor system, it is possible to suppress radiated noise from the motor wiring. Furthermore, the inverter device 2, the radiator 6 and the motor 3 are integrated, and the power converter system can be made compact.

  Further, as in the power converter system 700 shown in FIG. 7, the inverter device 2, the radiator 6, the frame 4 containing the motor 3, and the grounding capacitor 7 may be covered with an outer casing 14. As shown in the power converter system 800 shown in FIG. 8, a common mode coil 10 is additionally provided in each phase of the wiring between the AC system power supply 1 and the input unit of the inverter device 2 that is a power converter. The inverter device 2, the radiator 6, the frame 4 housing the motor 3, the grounding capacitor 7, and the common mode coil 10 may be covered with an outer casing 14. With such a structure, the same effect as that of the power converter system according to the fourth embodiment can be obtained, and radioactive noise from each part of the power converter system can be suppressed. Furthermore, the power converter system can be further downsized.

  In the power converter system according to the present invention, since the high-frequency common mode current leaking to the ground is suppressed, the conduction noise flowing out to the system power line is small, and there is no effect on the electronic equipment connected to the system power line. It can be effectively used as a highly reliable power converter system.

1 is a schematic cross-sectional view of a power converter system according to Embodiment 1. FIG. 6 is a schematic cross-sectional view of a power converter system according to Embodiment 2. FIG. 6 is a schematic cross-sectional view of a power converter system according to Embodiment 3. FIG. The power converter system according to the third embodiment is a power converter in which three types of elements of an inductance element, a resistance element, and an insulating material element are used in parallel for connection between a motor frame and a ground. It is a cross-sectional schematic diagram of a system. 6 is a schematic cross-sectional view of a power converter system according to Embodiment 4. FIG. FIG. 10 is a schematic cross-sectional view of a power converter system according to a fifth embodiment. FIG. 10 is a schematic cross-sectional view of a power converter system according to Embodiment 5 in which an inverter device, a frame housing a motor, and a grounding capacitor are covered with an outer casing. A cross section of a power converter system according to a fifth embodiment in which an inverter device, a radiator, a frame housing a motor, a grounding capacitor, and a common mode coil are covered with an outer casing. It is a schematic diagram.

Explanation of symbols

1 system power supply, 2 inverter device, 3 motor, 4 frame, 5 stray capacitance,
6 radiator, 7 grounding capacitor, 8 earth ground, 9 impedance element,
10 common mode coils, 11 inductance elements, 12 resistance elements,
13 Insulating material element, 14 Outer casing,
100, 200, 300, 400, 500, 600, 700, 800 Power converter system.

Claims (9)

An inverter device, a motor connected to the output unit of the inverter device, a grounding capacitor that connects each phase of wiring connecting the input unit of the inverter device and a system power supply, and a radiator of the inverter device, and A power converter system comprising a frame that houses a motor and is connected to the radiator, and an impedance element that connects the frame to a ground. The power converter system according to claim 1, wherein an insulating material element is used as the impedance element. 2. The power converter system according to claim 1, wherein a common mode coil is provided in each phase of the wiring between the system power supply and the input unit of the inverter device. 2. The power converter system according to claim 1, wherein any one of an inductance element and a resistance element, an inductance element, and a resistance element connected in parallel is used as the impedance element. The power converter according to claim 1, wherein the impedance element is used in parallel with any one of an inductance element and a resistance element, an inductance element, and a resistance element connected in parallel with an insulating material element. system. An inverter device, a motor connected to the output unit of the inverter device, a grounding capacitor that connects each phase of wiring connecting the input unit of the inverter device and a system power supply, and a radiator of the inverter device, and A frame that houses the motor and is connected to the radiator, an outer casing that covers the frame and that is connected to a ground, and an impedance element that connects the frame and the outer casing. A power converter system characterized by that. The power converter system according to claim 6, wherein the inverter device, the radiator, and the frame are covered with an outer casing. The power converter system according to claim 6, wherein the grounding capacitor, the inverter device, the radiator, and the frame are covered with an outer casing. A common mode coil is additionally provided in each phase of the wiring between the system power supply and the input unit of the inverter device. The common mode coil, the grounding capacitor, the inverter device, the radiator, and the frame are covered with an outer casing. The power converter system according to claim 6, wherein

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