JPH04255428A - Power supply for driving motor - Google Patents

Abstract

PURPOSE:To operate another AC load with excessive power of a solar cell panel when a motor(compressor) is not operating. CONSTITUTION:A lowpass filter is constituted of a capacitor 34 and the stator windings 37-39 of a motor. When the motor is not operating, switching contact pieces 32, 33 are switched to connect the lowpass filter circuit between an inverter circuit 25 and output terminals 35, 36 thus producing a pseudo-sinusoidal single-phase AC power from the inverter circuit 25. Since a choke coil is not required with a lowpass filter for cutting off high frequency components of the pseudo-sinusoidal wave, excessive power of solar cell can be utilized for general AC load without increasing the power supply or additionally providing electric components.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a power source that supplies pseudo-sine wave AC power to a motor based on PWM theory from DC power obtained by rectifying and smoothing AC power from a commercial power source and DC power generated by a solar cell. The present invention relates to the use of surplus power from solar cells in a device.

0002

[Prior Art] A conventional motor that uses AC power from a commercial power source and DC power from a solar cell to drive an electric motor is as described in Japanese Utility Model Application Publication No. 146847/1983. There was something. The device described in this publication is equipped with a commercial AC power source and a DC power source (solar battery power source), and uses either the commercial AC power source or the DC power source to operate a compressor (electric motor) for an air conditioner. It was designed to be driven.

0003

[Problem to be Solved by the Invention] In such conventional technology, when the output of the DC power source is low enough to operate the air conditioner, the AC power source is used to operate the air conditioner and the DC power source is used to operate the air conditioner. When the output of the power source is sufficient, the output of the DC power source is used to operate the air conditioner.

[0004] That is, only one of the commercial AC power source and the DC power source has always been used to operate the air conditioner. For this reason, when the output of the DC power source is low, the output is cut off, resulting in a low usage efficiency of the DC power source, making it impossible to utilize the DC power source to its full potential.

[0005] In order to solve these problems, Japanese Patent Application Laid-open No. 1986-
An attempt was made as described in Japanese Patent No. 221013. The system described in this bulletin uses a commercial AC power source and a DC power source (solar cells) together, and when the output of DC power decreases, the compressor is operated by making up for the shortage from the commercial AC power source. It was designed to do this.

[0006] In an air conditioner configured as described above, when the air conditioner is operating, it is possible to fully utilize the DC output of the solar cells, but when the air conditioner is not operating, the solar cells can be used. It was unavailable. For example, if we take this air conditioner as an example, in a general air conditioner dedicated to cooling, the period of cooling operation is from July to September of the year.
For models called cooling and dry, it is a four-month period from June to September.
For models called dry, a total of 8 months from June to September and from December to March was the typical operating period for air conditioners, that is, the period during which solar cells could be used. Therefore, under normal circumstances, solar cells are not used for 1/3 to 2/3 of a year.

The present invention solves these problems by making it possible to effectively utilize surplus power generated by solar cells when an electric motor (for example, an electric motor for driving a compressor of an air conditioner) is not operating. The present invention provides a power supply device as described above.

[0008]

[Means for Solving the Problems] The present invention provides a rectifying and smoothing circuit that rectifies and smoothes AC power supplied from an AC power source into DC power, and converts this DC power into a pseudo sine wave of any frequency based on PWM theory. In a power supply device that includes an inverter circuit that converts the pseudo sine wave AC power to a motor, the power supply device includes a solar cell, and converts the DC power of the solar cell into a voltage approximately equal to the voltage of the DC power; or a voltage control circuit that converts the voltage to a voltage slightly higher than the voltage of the DC power and supplies the voltage to the inverter circuit; and a low-pass filter configured using a capacitor and a stator winding of the motor when the motor is not operated. circuit and
When the motor is not operating, the DC power output from the voltage control circuit is converted into pseudo-sine wave AC power by an inverter circuit, and then it can be supplied to other AC loads via the low-pass filter.

The invention also includes a storage battery that stores the power generated by the solar cell, and a storage battery that converts the power of the storage battery into DC power having a voltage approximately equal to the voltage of the DC power or slightly higher than the voltage of the DC power, and converts the power of the storage battery into DC power that is connected to the inverter. a voltage control circuit that supplies a voltage to the circuit, and a low-pass filter circuit that is connected using a capacitor and a stator winding of the motor when the motor is not operating, and a low-pass filter circuit that is connected to the voltage control circuit when the motor is not operating. The inverter circuit converts the DC power into pseudo-sine wave AC power, which can then be supplied to other AC loads via the low-pass filter.

0010

[Operation] Using the power supply device configured as described above, it is possible to convert the electric power generated by the solar cell into AC power and supply it to a general AC load when the electric motor is not in operation. At this time, by using the stator winding of the motor as a low-pass filter, it becomes possible to supply AC power to a general AC load without adding a large-capacitance inductance element.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is an electrical circuit diagram of a main part of a separate air conditioner configured to drive a compressor motor using a power supply device according to an embodiment of the present invention (mainly an electrical circuit diagram of an outdoor unit)
It is.

In this figure, 1 is an indoor unit;
It is connected to the microprocessor 2 of the outdoor unit via a serial signal circuit 3 and a signal line so that control data can be sent and received.

The data sent from the indoor unit 1 includes a frequency signal F that determines the frequency of pseudo-sine wave AC power supplied to the compressor (compressor stops when F=0), cooling/heating signal (four-way valve signal for switching).

On the other hand, the data sent to the outdoor unit (from the microprocessor 2 to the indoor unit 1) includes outdoor temperature data, the frequency of the AC power currently being output (rotational speed of the compressor motor), and information about abnormalities in the outdoor unit. This includes data that indicates an abnormality when a situation occurs.

4 to 6 are single-phase induction motors (operating capacitors are omitted) for driving fans installed to blow air to the outdoor heat exchanger, respectively, and motors for high-temperature refrigerant discharged from the compressor during heating operation. Solenoid valve that opens the bypass pipe to return part of the water to the evaporator, reverses the refrigeration cycle and operates the cooling operation/
It is a four-way valve that switches between heating operations and is connected between the power bus bars of a commercial AC power source.

An opening/closing contact piece 7 and a switching contact piece 8 are connected in series to the induction motor 4. Switching contact piece 8
By switching the rotation speed of the induction motor 4, it is possible to change the rotation speed of the induction motor 4 into two stages: high speed and low speed. The operations of the opening/closing contact piece 7 and the switching contact piece 8 are controlled by the microprocessor 2.

Numerals 9 and 10 are phototriacs whose ON/OFF is controlled by the microprocessor 2. The electromagnetic valve 5 and the four-way valve 6 are energized by turning the phototriac ON/OFF. still,
The ON/OFF of the phototriacs 9 and 10 is controlled by the microprocessor 2.

Temperature sensors 11, 12, and 13 detect the outside air temperature, the temperature of the outdoor heat exchanger, and the temperature of the compressor 14, respectively. The microprocessor 2 controls the rotation speed of the induction motor by switching the switching contact 8 based on the outside air temperature and the temperature of the outdoor heat exchanger, and prevents this temperature from exceeding a predetermined value based on the temperature of the compressor 14. A protective operation is performed to forcibly reduce the frequency of AC power supplied to the compressor 14.

The compressor 14 uses a three-phase induction motor in which three stator windings are connected in a star shape as a driving source.

Reference numeral 15 denotes a commercial AC power supply, and AC power supplied from this power supply is applied to a rectifier circuit (diode bridge) 19 via a varistor 16, a noise filter 17, and a choke coil 18. This rectifier circuit 19 uses AC power (effective value 10
0V AC power) is voltage doubled and rectified together with capacitors 20 and 21 to obtain 280V DC power. 22 is a noise filter, and 23 is a smoothing capacitor. Note that 24 is a current fuse.

Reference numeral 25 denotes an inverter circuit, which consists of six switching elements (transistors, FETs, IGBTs, etc.) connected in a three-phase bridge configuration and a drive circuit 26 that turns these switching elements on and off individually. There is.

The drive circuit 26 is the microprocessor 2
O of the switching element according to the switching signal from
Controls N/OFF (power amplifies the switching signal from the microprocessor 2 to the extent that it can sufficiently drive the switching element). Therefore, each switching element of the inverter circuit 25 is connected to the microprocessor 2.
It will be turned on/off by the signal from.

The microprocessor 2 outputs a switching signal to the inverter circuit 25 so that the AC power of the frequency signal given from the indoor unit is supplied to the compressor 14. This switching signal is generated based on the PWM theory (the magnitude of the carrier wave and the modulated wave of the frequency of the frequency signal).
This is a switching signal calculated and calculated by the microprocessor 2 based on .

Therefore, the compressor 14 can be supplied with alternating current power of any frequency (alternating current power generated by a pseudo sine wave). It goes without saying that by changing the frequency of this alternating current power, the rotational speed of the electric motor that drives the compressor changes and the capacity of the compressor can be changed.

27 is a switching power supply, 280V
DC power is reduced to a low voltage necessary for the operation of the microprocessor 2 and other electronic circuits.

Reference numeral 28 denotes a solar cell panel (a panel formed by connecting a plurality of solar cells), and has a maximum output of, for example, about 600W. (In this embodiment, it is about 1/3 of the maximum power consumption of the compressor 14, and is set appropriately according to the maximum power consumption.) 29 is a DC/DC converter (voltage control circuit) and is a solar cell panel. The output from 28 is 2
It steps down (or steps up) the voltage to 90V. This 29
0V is not limited to this voltage, and may be any voltage (voltage after subtracting the voltage drop caused by the diode 30) higher than the voltage (280V) that has been voltage-doubled and rectified by the rectifier circuit 19 and capacitors 20 and 21.

By setting the voltage in this way, D
The DC output of the C/DC converter 29 is transferred to the inverter circuit 2.
In addition, when the output of the DC/DC converter 29, that is, the output of the solar cell decreases, when the output of the solar cell is insufficient and the power voltage decreases, the power from the AC power source 15 is supplied. , inverter circuit 2
5 is always supplied with the necessary power.

Reference numeral 30 denotes a backflow prevention diode, which prevents direct current by voltage doubler rectification when the output of the solar panel decreases or when the power consumption of the compressor 14 increases and the output of the solar panel 28 becomes insufficient. Power comes from solar panel 2
This prevents the water from flowing back into the air.

Reference numeral 31 is a storage battery (connected in the second embodiment), which stores surplus power from the solar battery.

Reference numerals 32 and 33 are interlocking switching contacts whose switching is controlled by the microprocessor 2. The switching contacts 32, 33 are connected between the inverter circuit 25 and the stator winding of the motor of the compressor 14. When the switching contacts 32, 33 are in the state shown in FIG. 1, AC power with a pseudo sine wave from the inverter circuit 25 is supplied to the compressor 14, and the switching contacts 32, 33 are in the state shown in FIG. In this state, the pseudo sine wave AC power from the inverter circuit 25 is supplied to other AC loads from the AC output terminals 35 and 36 via the capacitor 34.

The stator windings of the compressor 14 are arranged at 37 and 38, respectively.
, 39, the flow of AC power output from the inverter circuit 25 is as shown by the solid line in FIG. At this time, the inverter circuit 25 has a frequency of 50 hertz (or 60 hertz).
The microprocessor 2 outputs a switching signal so that single-phase pseudo-sine wave AC power (0 Hz) is output from terminals corresponding to the stator windings 37 and 39.

In the figure, first, the single-phase AC output from the inverter circuit 25 is transmitted through the inverter circuit 25→switching contact piece 32→terminal 35→other AC load→switching contact piece 33→fixed winding as shown by the solid arrow. 39→Fixed winding 37→
The signal flows in the order of the inverter circuit 25. At this time capacitor 3
4 is connected between the output terminal 35 and the output terminal 36, and forms a low-pass filter together with the stator windings 37 and 39. FIG. 3 shows the wiring of this low-pass filter.

FIG. 3 shows the switching contact pieces 32, 33 shown in FIG.
FIG. 3 is an electrical circuit diagram of a low-pass filter that is in the state shown in the figure. In this circuit diagram, the compressor 14
The stator windings 37 and 39 act together with the stator core as a choke coil. An AC load up to the power consumption range allowed by the inverter circuit 25 can be connected to the output terminals 35 and 36. Therefore, this low-pass filter also needs a capacity that can tolerate this power consumption. In this embodiment, the choke coil, which can supply the compressor 14 with a maximum output of 1.2 kilowatts by combining the generated power of the solar cell 28 and the output of the AC power source, also needs to have the same capacity. However, since the capacity of the compressor 14 corresponds to this capacity, when the stator winding of the compressor 14 is used as a choke coil, this choke coil will not exceed its capacity. Therefore, a low-pass filter can be constructed without newly providing a choke coil with a large capacity corresponding to an output of 1.2 kilowatts.

By supplying the pseudo sine wave AC power output from the inverter circuit 25 to other AC loads via a low-pass filter, harmonic components contained in the pseudo sine wave can be blocked, making it possible to block the harmonic components contained in the pseudo sine wave. It can drive an AC load in the same way as an AC power source.

FIG. 4 shows the microprocessor 2 shown in FIG.
3 is a flowchart showing the main operations of FIG. In this figure, the operation of the microprocessor 2 is first started in step S1, and then the microprocessor 2 is initialized in step S2. Next, in step S3, it is determined whether or not this air conditioner is in operation. For example, determining whether the operation switch is turned on or not,
When the operation switch is a push switch or a tact switch, the microprocessor 2 determines whether it is in operation mode or stop mode.

Next, when the operating state is determined in step S3, the process advances to step S4 and step S5. In these steps, the switching contacts 32 and 33 are set to the state shown in FIG. 1 to perform normal operation. That is, pseudo sine wave AC power having a frequency based on the frequency signal sent from the indoor unit 1 is outputted from the inverter circuit 25 to the compressor 14 . At this time, a pseudo sine wave is created using the power generated by the solar cell and the power from the AC power supply.

When it is determined in step S3 that the air conditioner is not in operation, that is, when it is determined that there is no need to drive the compressor, steps S6 and S7 are performed, and the switching contacts 32 and 33 are turned on. After switching to the state shown in FIG. 2, the frequency signal sent from the indoor unit is fixed at 50 hertz.

Next, the process advances to step S10 and the frequency is set to 50.
Outputs Hertz single-phase pseudo sine wave alternating current. Note that in order to obtain a single-phase pseudo sine wave, two of the six switching elements constituting the three-phase bridge of the inverter circuit 25
The switching elements are always set to OFF state, and the four switching elements that make up the single-phase bridge are turned ON/OFF.
It is used to obtain single-phase output by flip-flopping.

By controlling in this way, 50 Hz single-phase AC power is supplied to the load from the output terminals 35 and 36 using the power generated by the solar panel 28 and the power from the AC power supply. It is.

Next, the second embodiment will be explained.
In this embodiment, a storage battery 31 for storing surplus power of the power generated by the solar panel 28 is connected to the DC/DC converter 29 shown in FIG. 1 (this storage battery may be used in the previous embodiment). , the connection point of the cathode of the diode 30 is connected between the current fuse 24 and the inverter circuit 25, and a switch is further inserted at the same position as the current fuse 25, so that the power of the AC power supply 15 is not supplied to the inverter circuit 25. This is how it was done.

FIG. 5 is a flowchart showing the operation of this embodiment, and the difference from the previous embodiment shown in FIG. 4 is that step S8 and step S9 are inserted.

In steps S8 and S9, it is determined whether the power generation power of the solar panel 28 can withstand the power consumption of the AC loads connected to the output terminals 35 and 36, and the power generation power of the solar panel 28 is determined. Insufficient output terminals 35, 36
When a voltage drop occurs in the inverter circuit 25
AC power output is stopped without driving. This determination is made, for example, from the magnitude of the voltage drop in the DC power applied to the inverter circuit 25. At this time, a display indicating that the amount of power generated by the solar panel is insufficient may be displayed.

Further, when the power generated by the solar panel 28 exceeds the power consumption of the AC load connected to the output terminals 35 and 36, this surplus power is directly converted into thermal energy and the like and released. This surplus power is stored in the storage battery 31 in order to effectively utilize this surplus energy. By using this storage battery, it is possible to use an AC load even when the power generated by the solar cell panel 28 is small or at night without relying on an AC power source.

In the embodiments described above, the choke coil used in the low-pass filter is composed of the stator winding and the stator core of the compressor, but originally the stator winding and the stator core were not connected to the choke coil. It is not designed for coils, and when pseudo-sine wave AC power is supplied, losses due to eddy currents and heat occur. Such losses can be reduced by increasing the frequency of the carrier wave when generating the pseudo sine wave to an extent that does not cause magnetic saturation of the stator core. Therefore, when considering this loss, it is recommended to configure the inverter circuit 25 using high frequency compatible switching elements such as FETs (field effect transistors) and IGBTs (insulated gate bipolar transistors) to increase the frequency of the carrier wave. good.

[0045]

Effects of the Invention The present invention provides a power supply device that supplies a motor with pseudo-sine wave AC power generated based on PWM theory using a solar cell and a commercial AC power supply. A low-pass filter is constructed using the fixed windings of the motor and the pseudo-sine wave AC power is supplied to other AC loads using this low-pass filter. Therefore, a choke coil is used to configure the low-pass filter. This makes it possible to supply pseudo-sine wave AC power to general AC loads without the need for a new installation. Therefore, there is no need for a space to provide a choke coil large enough to withstand a large output, making it possible to downsize the device. At the same time, the solar cells can be used effectively even when the motor is not being driven, increasing the efficiency of using electrical energy.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram of an air conditioner using an embodiment of the present invention.

FIG. 2 is an electric circuit diagram showing another state of the switching contact piece shown in FIG. 1;

FIG. 3 is an equivalent circuit diagram of the electrical circuit diagram shown in FIG. 2;

FIG. 4 is a flowchart showing the operation of the microprocessor shown in FIG. 1;

FIG. 5 is a flowchart showing the operation of another embodiment of the present invention.

[Explanation of symbols]

14 Compressor 15 AC power supply 25 Inverter circuit 28 Solar panel 29 DC/DC converter 30 Diode 32 Switching contact piece 33 Switching contact piece 34 Capacitor 35 Output terminal 36 Output terminal 37 Stator winding 38 Stator winding 39 Stator winding

Claims (4)

[Claims] Claim 1: A rectifying and smoothing circuit that rectifies and smoothes AC power supplied from an AC power source into DC power, and an inverter circuit that converts this DC power into a pseudo sine wave of an arbitrary frequency based on PWM theory. , a power supply device configured to supply this pseudo-sine wave AC power to a motor includes a solar cell and a DC power of the solar cell that is set to a voltage approximately equal to the voltage of the DC power, or slightly less than the voltage of the DC power. a voltage control circuit that converts the voltage into a high voltage and supplies it to the inverter circuit; a low-pass filter circuit configured using a capacitor and a stator winding of the motor when the motor is not operated; A power supply device for driving a motor, characterized in that DC power output from the voltage control circuit is converted into pseudo-sine wave AC power by an inverter circuit, and then supplied to another AC load via the low-pass filter. . 2. The power supply device for driving a motor according to claim 1, wherein the frequency of the pseudo sine wave AC power supplied to the other AC load is 50 hertz or 60 hertz. 3. A rectifying and smoothing circuit that rectifies and smoothes AC power supplied from an AC power source into DC power, and an inverter circuit that converts this DC power into a pseudo sine wave of an arbitrary frequency based on PWM theory. A power supply device configured to supply this pseudo-sine wave alternating current power to an electric motor includes a solar cell, a storage battery that stores the power generated by the solar cell,
a voltage control circuit that converts the power stored in the storage battery into DC power having a voltage approximately equal to the voltage of the DC power or slightly higher than the voltage of the DC power and supplies the converted power to the inverter circuit; and a low-pass filter circuit configured using a capacitor and a stator winding of the motor when the motor is not operating, and converts DC power output from the voltage control circuit into a pseudo sine wave using the inverter circuit when the motor is not operating. A power supply device for driving a motor, characterized in that the AC power is converted into AC power and then supplied to other AC loads via the low-pass filter. 4. Claim 1, characterized in that the frequency of the carrier wave when generating the pseudo sine wave alternating current based on PWM theory is set to a frequency sufficiently higher than the frequency of the modulated wave.
A power supply device for driving an electric motor according to claim 3.