JP2018186663A - Power Conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conditioner capable of reducing a noise from a reactor.SOLUTION: A power conditioner comprises: a terminal base 103 for connecting between wiring from a DC power generation device and wiring to a commercial power supply system; a DC-DC converter device 105 that steps up a DC output voltage of the DC power generation device; and a system interconnection inverter device 106 that converts an output power of the DC-DC converter device into an AC power. A noise from the DC-DC converter device and a reactor of the system interconnection inverter device is detected by noise detection means 402. A calculation device of a controller 401 detects a frequency of a noise larger than a displeasing prescribed level within a range of an audible frequency by frequency analysis calculation, such as FFT (Fast Fourier Transformation), calculates a carrier frequency that avoids an integer multiple of the detected frequency of the noise within such a range that performance of an inverter device and a converter device can be maintained, and drives semiconductor switching elements 105a and 106a to 106d.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a power conditioner that converts DC power into AC power corresponding to the frequency of a commercial power system, and more particularly to noise prevention by driving a semiconductor element of a power conditioner for a photovoltaic power generation system.

  In recent years, a photovoltaic power generation device (solar power generation) as a grid-connected power generation device that not only uses electric power generated by sunlight as an energy source but also supplies surplus power not used by the home to a commercial power supply system. System) is widespread.

  In this solar power generation system, the DC power generated by the solar cell is converted into AC power corresponding to the frequency of the commercial power system by the power supply device, and the generated power is used for private use and surplus power is supplied to the commercial power system. Yes. This power supply device is generally called a power conditioner.

  A power conditioner includes a DC-DC converter device that boosts an unstable output voltage from a solar battery, and a system that converts DC power output from the DC-DC converter apparatus into AC power corresponding to the frequency of a commercial power system. A connected inverter device is provided. In addition, a heat sink for dissipating heat from the DC-DC converter device and the system-linked inverter device is provided, and a semiconductor switching element of the DC-DC converter device and the inverter device is used as a heat sink using an insulating means such as an insulating sheet. Fixed.

  The DC-DC converter device uses a reactor for the purpose of introducing reactance into the circuit for smoothing current pulsation, because the DC-DC converter device is used for boosting or stepping down the DC voltage.

  Since such a power conditioner is installed in a house and requires quietness, a cooling fanless configuration in which a heat dissipation method is naturally air-cooled is increasing recently.

  In such a power conditioner, noise from the reactor of the converter device or the inverter device may be a problem. That is, there is a problem that noise is caused by vibrations in the air due to magnetostriction caused by fluctuations in the magnetization intensity of the reactor at the driving period of the semiconductor switching element, that is, the carrier frequency.

  This noise increases due to resonance when the carrier frequency is an integer multiple of the natural frequency depending on the structure and size of the reactor. In addition, the natural frequency varies depending on the manufacturing variation of the reactor, assembly, mounting state, varnish impregnation state, core gap material adhesion state, and the degree of propagation to the outside depends on the mounting position of the power conditioner and the mounting state of the mounting plate. Change.

  When the noise caused by these is a human sensitive region (for example, about 100 Hz to 4 kHz) in a human audible region (generally 20 Hz to 20 kHz), the power conditioner is a source of annoying noise. .

In Patent Literature 1, noise outside the vehicle is detected by a noise level sensor in the vehicle power converter,
In a situation where the noise noise caused by the carrier frequency is drowned out by the traveling noise, a method for lowering the carrier frequency to an audible range with good conversion efficiency is described.

JP 2006-333572 A

  However, the method of Patent Document 1 is effective in a noisy environment because of the idea that noise depending on the carrier frequency is mixed into a large ambient noise, but cannot be expected in a quiet environment.

  The objective of this invention is made | formed with respect to the above subjects, and is reducing the noise from a reactor in the environment where surroundings are quiet.

The above issues
A regulation that detects noise from a reactor with noise detection means such as a microphone or vibration detection means, and feels uncomfortable within the range of audible frequencies by frequency analysis calculation such as FFT (Fast Fourier Transform) with the arithmetic unit of the control unit Detecting the frequency of noise exceeding the level of, and calculating the carrier frequency that avoids integer multiples of the detected noise frequency in a range where the performance of the inverter device and the converter device can be maintained, driving the semiconductor switching element,
It is improved by the power conditioner characterized by this.

  According to the power conditioner of the present invention, the resonance of the reactor due to the carrier frequency is suppressed, and the noise can be reduced.

It is a figure which shows the solar energy power generation system structure in this embodiment. It is a figure which shows the example of a power conditioner external appearance. It is a figure which shows an example of the product structure of a power conditioner. It is a figure which shows an example of the circuit structure of a power conditioner.

  Embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

  As shown in FIG. 1, the solar power generation system of this embodiment includes a plurality of solar cell arrays 100a and 100b (hereinafter, collectively referred to as “solar cell array 100”) that are direct-current power generators. A connection box 101 that collects wiring from the power supply system, a grid-connected power conditioner 102 that converts DC power from the solar cell array 100 supplied via the connection box 101 into AC power, and an output side of the power conditioner 102 The power distribution unit 109 provided in the power distribution unit 109 and the power sensor unit 110 that detects the power flowing through the distribution panel 109 are configured to cause the power generated by the solar cell array 100 to flow backward to the commercial power supply system 111. .

  Further, the power conditioner 102 includes a terminal block 103 that connects the wiring from the solar cell array 100 and the wiring to the distribution board 109, and a filter circuit that suppresses electrical noise of DC output power supplied from the terminal block 103. 104, a DC-DC converter 105 that boosts the DC output voltage output from the filter circuit 104, and a system-linked inverter that converts the DC output voltage from the DC-DC converter 105 into AC power corresponding to the frequency of the commercial power supply system 111 106, a filter circuit 107 that suppresses electrical noise of AC power output from the system linkage inverter 106, and a system linkage relay 108 that turns on / off the connection with the commercial power supply system 111.

  Next, the external appearance of the power conditioner 102 will be described with reference to FIG. FIG. 2 is a perspective view of the power conditioner 102 displayed through a front panel 306 described later. As shown here, the power conditioner 102 is provided with a display device 200 for displaying an operation state, an error, and the like on the front surface, and the terminal block 103 described above is provided therein.

  FIG. 3 is an exploded perspective view of the power conditioner 102. As shown here, the main substrate 300, the sub substrate 301, the heat sink 302, the display device 200, and the terminal block 103 are disposed inside the power conditioner 102. The power conditioner 102 is covered with an outer upper case 303, an outer lower case 304, a rear case 305, and a front panel 306. In addition, what is not required to understand this embodiment among those shown in FIG. 3 is omitted.

  Next, components disposed on each of the terminal block 103, the main board 300, and the sub board 301 will be described in detail with reference to FIG.

  As shown in FIG. 4, the terminal block 103 is provided with terminals 103a to 103h. Among these, the terminals 103 a and 103 b are connected to the connection box 101, and the terminals 103 c and 103 d are connected to the distribution board 109. The terminals 103a and 103e, the terminals 103b and 103f, the terminals 103c and 103g, and the terminals 103d and 103h are electrically connected to each other.

  A filter circuit 104, a DC-DC converter 105, a system linkage inverter 106, a filter circuit 107, a system linkage relay 108, and a gate driver 403 are mounted on the main board 300. The main board 300 is fixed on the heat sink 302. ing. The heat sink 302 is made of a conductive material such as metal and is connected to a ground conductor. The heat sink 302 is fixed in contact with the switching elements 105a and 106a to 106d of the DC-DC converter 105 and the system linkage inverter 106 via an insulating sheet, and efficiently dissipates the switching elements 105a and 106a to 106d.

  On the sub-board 301, a power supply 400 for operating electronic components and the like, and a control unit 401 are mounted. The control unit 401 transmits a switching signal for controlling the ON / OFF operation of the switching element 105 a of the DC-DC converter 105 and the switching elements 106 a to 106 d of the system linkage inverter 106 to the gate driver 403 and turns on the system linkage relay 108. / OFF, display on the display device 200, and a speaker (not shown) are controlled.

  A switching element 105a, a capacitor 105b, and a DC reactor 105c are provided in the DC-DC converter 105, and a signal is transmitted from the control unit 401 to the gate driver 403 to control the ON / OFF operation of the switching element 105a. Thus, the DC power input through the terminal block 103 can be boosted, and the DC power of a desired voltage can be output from the capacitor 105b. In the grid interconnection inverter 106, switching elements 106a to 106d and an AC reactor 106e are provided, and a signal is transmitted from the control unit 401 to the gate driver 403 to control the ON / OFF operation of the switching elements 106a to 106d. AC power having a frequency corresponding to the frequency of the commercial power supply system 111 can be output from the system linkage inverter 106. The above ON / OFF operation is controlled by PWM (Pulse Width Modulation). PWM is a power control method in which a constant period of ON and OFF of a pulse is generated and the ON time width is changed. This constant period of ON and OFF is called a carrier frequency. In the present embodiment, the noise of the reactor is detected by the microphone 201 which is the noise detecting means 402, and it is uncomfortable within the audible frequency range by the frequency analysis calculation such as FFT (Fast Fourier Transform) by the calculation unit of the control unit 401. A semiconductor switching element that detects a frequency of noise exceeding a specified level and calculates a carrier frequency that avoids an integer multiple of the detected noise frequency within a range in which the performance of the DC-DC converter 105 and the grid interconnection inverter 106 can be maintained. 105a and 106a to 106d are driven at the calculated carrier frequency.

  In the present embodiment, the microphone 201 is used as noise detection means. However, the resonance frequency may not be detected by the microphone 201. For example, a vibration sensor may be installed in the reactor or in the vicinity thereof.

  As described above, according to the present embodiment, the resonance of the reactor due to the carrier frequency is suppressed, and a low-noise power conditioner can be provided.

  In the present embodiment, the solar cell array is introduced as an example of the DC power generator, but the application target of the present invention is not limited to this, and for example, a fuel cell may be used as the DC power generator.

100, 100a, 100b Solar cell array 101 Junction box 102 Power conditioner 103 Terminal block 104, 107 Filter circuit 105 DC-DC converter 105a Switching element 105b Capacitor 105c DC reactor 106 System linkage inverter 106a-d Switching element 106e AC reactor 108 System Linkage relay 109 Distribution board 110 Power sensor unit 111 Commercial power supply system 200 Display device 201 Microphone 300 Main board 301 Sub board 302 Heat sink 400 Power supply 401 Control unit 402, Noise detection means 403 Gate driver

Claims (5)

A terminal block for connecting the wiring from the DC power generator and the wiring to the commercial power supply system;
A DC-DC converter that boosts the DC output voltage of the DC power generator using a first semiconductor switching element and a DC reactor;
A grid-connected inverter that converts output power of the DC-DC converter into AC power using a second semiconductor switching element and an AC reactor;
A heat sink for dissipating heat generated from the DC-DC converter and the grid interconnection inverter;
A power source to which DC power from the DC power generator is input;
A gate driver for controlling the DC-DC converter and the grid-linking inverter;
A controller for supplying a switching signal to the gate driver;
A filter circuit that reduces noise,
The noise from the reactor of the DC-DC converter and the grid-connected inverter is detected by a noise detection means, the frequency of the noise is calculated by the frequency analysis calculation by the calculation unit of the control unit, and an integer multiple of the obtained noise frequency A power conditioner that drives a semiconductor switching element by a carrier frequency that avoids the above. In the power conditioner of Claim 1,
The power conditioner is characterized in that the noise detecting means comprises a microphone. In the power conditioner according to claim 1 or 2,
The power conditioner is characterized in that the noise detecting means comprises a vibration sensor. In the power conditioner according to claims 1 to 3,
The power conditioner characterized in that the noise detecting means is arranged in the vicinity of a reactor. A solar cell array,
The power conditioner according to any one of claims 1 to 4, wherein the solar cell array is the DC power generator.
A connection box for connecting the solar cell array and the power conditioner;
A distribution board for connecting the power conditioner and the commercial power supply system;
A photovoltaic power generation system comprising:

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