JP5664601B2 - Room air conditioner - Google Patents

Description

  The present invention is a DC power supply device and a device that uses the DC power supply device, particularly those that improve the power factor used in a cooling air conditioner, etc., and suppresses harmonics on the AC power supply side to reduce the generation amount below the limit value of the harmonic regulation. Related to large fluctuations on the power supply side and load side.

  FIG. 6 is a block diagram showing a configuration of a conventional DC power supply device disclosed in Japanese Patent Laid-Open No. 9-247943. In FIG. 6, 1 is an AC power source, 2 is a full-wave rectifier circuit composed of four diodes for full-wave rectification of the voltage of the AC power source 1, and 3 is connected at one end to the positive output side of the full-wave rectifier circuit 2, DC reactor 4 for storing energy and smoothing current 4 is a smoothing unit for smoothing the DC bus voltage provided between the other end of DC reactor 3 and the negative output side of full-wave rectifier circuit 2. A capacitor 5 is a reverse current blocking diode that is provided between the other end side of the DC reactor 3 and the positive side of the smoothing capacitor 4 and prevents current from flowing backward from the smoothing capacitor 4 side to the full-wave rectifier 2.

  6 is provided between the other end of the DC reactor 3 and the negative output side of the full-wave rectifier circuit 2 and switches between the DC buses, 7 is a load connected in parallel to the smoothing capacitor 4, and 8 is an AC Control means for controlling opening / closing of the switch means 6 at an opening / closing time selected by the selection means described later at least twice in a half cycle of the power supply based on the power supply synchronization signal generated from the voltage of the power supply 1, and 9 is according to the load amount of the load 7 Storage means for storing data of opening / closing time of the switch means 6 set in advance, 10 is a load amount detection means for detecting the load amount of the load 7, and 11 is a load amount detected by the load amount detection means 10. Accordingly, it is a selection means for appropriately selecting a switch opening / closing time stored in advance in the storage means 9.

  Next, the operation will be described. When the switch means 6 as shown in FIG. 6 is used and the switch means 6 is operated only several times during a period in which the input current does not flow, during the operation of the switch means 6, the full-wave rectifier 2, A current path that passes through the DC reactor 3, the switch means 6, the full-wave rectifier 2, and the AC power supply 1 is formed. If the switch means 6 is turned on and closed, the input current will not be interrupted even if the switch means 6 is opened thereafter. This is due to the nature of the direct current reactor 3, and the reactor has the property of continuing to flow current. Therefore, the energy stored in the reactor is charged into the smoothing capacitor 4, whereby the input current flows. Therefore, the input current continues to flow until the energy stored in the DC reactor 3 is consumed.

  FIG. 7 is a waveform diagram showing the relationship between the input current and the input voltage when the switch means 6 is operated only twice during the period in which the input current flows immediately after the zero cross point. Tsw1 is a first delay time until the switch means 6 is closed, Ton1 is a first closing time when the switch means 6 is closed, Tsw2 is a second delay time until the switch means 6 is closed, and Ton2 is a switch This is the second closing time when the means 6 is closed. When the switch means 6 is closed after passing the zero cross point, a current path is formed as described above, and a current flows. Even if the switch means 6 is opened, energy is accumulated in the direct current reactor 3, and the direct current reactor 3 works to pass the current by the amount of energy of the direct current reactor 3, and the switch means 6 before the current becomes zero. Perform the second switch operation. Then, after the switch means 6 is turned off for the second time, the input voltage becomes higher than the DC voltage and current flows, resulting in an input current waveform as shown in FIG. In this way, the phase difference between the voltage and the current is reduced and the power factor is improved by operating the switch means 6 to flow the current during the period when the input current does not flow. Further, by controlling the operation timing of the switch means 6, since the input current flows not only near the peak but also near the zero cross, harmonics are reduced.

  FIG. 8 shows a DC power supply device disclosed in Japanese Patent Publication No. 7-89743. In FIG. 8, the AC power source 1 is rectified via a reactor 20 and a rectifier circuit 2 having a bridge configuration, and supplies DC power to the load 7. Reference numeral 4 denotes a smoothing capacitor. Reference numeral 19 denotes a power supply side filter composed of a reactor and a capacitor, 6 denotes a power transistor as a switching means, and 5 denotes a backflow prevention diode. The voltage reference E0 set by the voltage setting unit 14 is compared with the DC load voltage E, the difference ΔE is amplified by the voltage control amplifier 15, and multiplied by the AC voltage signal v1 by the multiplier 16, and synchronized with the power supply phase. It is converted into an error signal Δv. The error signal Δv is compared with the load alternating current signal i1 detected by the current detector 40 by the comparator 17, and when Δv> i1, the logic output of the comparator 17 becomes 1, and the base drive of the power transistor 6 is reached. The power transistor 11 is turned on via the circuit 18, and when Δv <i1, the logic output of the comparator 17 becomes 0 and the power transistor 6 is turned off. When the power transistor 6 is turned on, the load side is short-circuited and the current i1 increases. When the power transistor 6 is turned off, the current i1 flows into the load side, that is, the backflow prevention diode 5, the smoothing capacitor 4 and the load 7 and decreases. When Δv> i1, the power transistor 6 is turned on again. On / off of the power transistor 6 is repeated at a switching frequency of several kHz determined by a current control delay element formed by the comparator 17. Accordingly, as shown in FIG. 9, the current i1 pulsates at the switching frequency and substantially synchronizes with the power supply voltage v. As a result, the power factor is maintained at 1 and the third, fifth, etc. harmonics are maintained. The waves are almost gone. Further, since the power supply side filter 19 including the reactor and the capacitor is added, the power supply voltage does not drop due to the overlapping angle of the rectifier when only the reactor 20 is used, and the waveform distortion of the voltage signal v1 provided as the synchronization signal can be removed.

  In the case of a room air conditioner, the inverter device for variable speed operation of the power supply device shown in the above prior art and the compressor or blower motor that is the load is housed in an outdoor unit, and is composed of a reactor and an electric circuit. The power supply device and the inverter device operate as a cooling / heating air conditioner using a refrigerant by driving a compressor or a blower.

  Use silicon carbide diodes for switching means snubber diodes that absorb commutation spike voltages that occur when switching in converter circuits and flywheeling diodes that smooth out sudden changes in the circuit caused by switching This is known from Japanese Patent Publication No. 11-510000. Further, improvement of power consumption by short-circuiting a backflow prevention diode in a power supply control circuit is known from Japanese Patent Application Laid-Open No. 11-332113. On the other hand, a heat exchanger is arranged in an air passage by a blower as a structure in an outdoor unit used for a cold air conditioner that performs air conditioning and refrigeration by circulating a refrigerant in a refrigeration cycle, and heat exchange is performed. In order not to obstruct the air path of the heat exchanger and the blower, the compressor is disposed on the side surface, and the reactor is disposed on the upper surface of the compressor. The compressor and the reactor, which are noisy and have a high temperature, are shielded by sheet metal and are further covered with a soundproof material, quinol. Further, electric circuit components are arranged on the entire upper surface, and the above-described switch means of the DC power supply device, the backflow prevention diode and the switch means of the inverter device are mounted therein. In addition, heat radiation fins for the switch means and the backflow prevention diode are mounted. In addition, noise countermeasure parts such as a choke coil are also mounted as countermeasures against electromagnetic noise on the power line.

Japanese Patent Laid-Open No. 9-247943 Japanese Patent Publication No. 7-89743 Japanese National Patent Publication No. 11-510000 Japanese Patent Laid-Open No. 11-332113

  The conventional technique shown in the previous section has many problems because it uses an ordinary silicon element as a circuit switching means and a diode for preventing backflow from the capacitor. First, since the backflow prevention diode is an element using ordinary silicon, the power loss due to the voltage drop is large, and the efficiency of the power supply device is lowered regardless of the switch of the switch means. This is a particularly big problem when applied to a cooling / air-conditioning apparatus whose efficiency performance is a basic performance. Also, since the temperature rise due to the loss of these backflow prevention diodes and the operating temperature limit is low because the backflow prevention diode is an element using silicon, it is necessary to attach large heat dissipation parts to the element, and it is applied to cold air conditioning equipment If so, the cold air conditioning equipment becomes larger. In addition, since the heat dissipating parts must be arranged in the air passage, there is a restriction on the arrangement place of the power supply device. For this reason, the size of the device becomes large, the wiring line to the DC power supply device becomes longer, the amount of electromagnetic noise generated in the power supply device increases, and the size and cost of countermeasure parts and the like are also significant issues.

  There are also many problems when the switching means is switched. First, when the reverse current prevention diode is conducting a current in the forward direction, the reverse current prevention diode is reverse biased when the switching means is turned on, but at that time, the reverse recovery charge in the PN junction region of the silicon diode is very large in a very short time. A recovery current is generated and flows through the switch means, which greatly increases the switch loss of the switch means. A silicon PN junction diode with a rated reverse breakdown voltage of 600V and a rated forward current of 6A that is generally used for power at present, has a reverse recovery charge of 150 to 1500 nc, and its operating temperature is guaranteed only up to 125 ° C. Therefore, a large loss occurs in the power supply device. The above-mentioned loss is a particularly big problem in the cooling and air-conditioning equipment in which efficiency performance is very important. It can be avoided by reducing the number of switches of the switch means of the DC power supply device to several times in the AC power supply cycle, or power factor When emphasizing the improvement effect, the conversion efficiency is inevitably sacrificed by setting the frequency to several kHz. In any case, a current ripple of several times or several kHz of the power cycle that is a human audible sound range is generated in the reactor for storing electric power at the time of switching, and a very large noise is generated from the reactor. Installation of soundproofing and soundproofing parts for reactor noise countermeasures, design restrictions and cost increase due to the need for soundproofing structure are significant. For this reason, there are many restrictions on the use of these power supply devices in air conditioning equipment, refrigerators, dehumidifiers and the like used in the living environment, which require quietness.

  In addition, when the number of switches is small, when trying to improve the power factor and reduce the amount of harmonics generated, the amount of energy that can be stored in the reactor must be increased each time, so a very large and heavy reactor is required. The power supply device is large in size, weight, and cost. This is a very big problem with dehumidifiers that are supposed to be originally carried. In some cases, the reactor for suppressing harmonics may be larger and heavier than the motor that generates the main function. Increasing the value of the reactor also increases the winding resistance value of the reactor, increasing the loss of the reactor and further reducing the efficiency of the power supply device. Further, the reverse recovery current described above has a very large time change in current, and a large amount of high frequency noise is generated at the time of switching. For this reason, noise countermeasure parts are required for countermeasures against electromagnetic noise, and choke coils are usually used for these countermeasure parts, which increases weight, size, and cost. Also, the power loss due to the resistance of the choke coil is large. Furthermore, in the case of a cooling / heating air conditioner, there are more restrictions on the arrangement of power supply units. Further, in the case of a solar battery or the like having a large power supply voltage variation as a DC power supply device, or a DC power supply device for a vehicle or the like having a large backflow from the load side, there are similar problems.

  The present invention has been made to solve the above-described problems, and provides a highly efficient, small, and lightweight power supply device without being limited by the type of power supply or load. The present invention provides an efficient and low noise power supply. The present invention provides a device with good performance and low cost.

An air conditioner of the present invention includes a rectifier circuit that rectifies alternating current from an alternating current power supply or a smoothing capacitor that smoothes a direct current voltage between direct current buses supplied from a direct current power supply, switch means disposed on the power supply side from the smoothing capacitor, and a switch A reactor arranged on the power supply side from the means for storing current energy, and arranged between the smoothing capacitor and the switch means to prevent a reverse flow from the smoothing capacitor to the power supply side, and forward and reverse voltages are applied when the switch means is off. A reverse current prevention diode having a wide gap energy band such as a silicon carbide semiconductor, a control means for opening and closing the switch means to control the rotational speed of the DC motor to a target rotational speed, a DC motor connected in parallel to a smoothing capacitor, Outside the air conditioner room that is the load of the inverter and the DC motor that are switched to synchronize And a compressor, in which with a.

The air conditioner of the present invention uses a wide gap semiconductor for the backflow prevention diode and uses a silicon semiconductor for the semiconductor parts other than the backflow prevention diode, so that it is possible to reduce the size and reduce power consumption. The Furthermore, since the switch means is opened and closed to control the rotational speed of the DC motor to the target rotational speed, the switch means is turned on only when there is a load on the motor, preventing unnecessary control and further power consumption. Can be reduced.

The block diagram which shows the structure of the DC power supply device of this invention. The circuit and block diagram of the load of the direct-current power supply device of this invention. The timing explanatory drawing which shows the circuit operation of the load of the direct-current power supply device of this invention, and the phase voltage of the motor of a DCBLM compressor. The block diagram which shows the structure of the DC power supply device of this invention. The three-way figure of the room air-conditioner outdoor unit structure when it is set as the inverter apparatus for carrying out the variable speed driving | operation of the compressor and fan of a room air-conditioner outdoor unit and its electric motor to the power supply device of this invention and its load. The block diagram which shows the structure of the conventional DC power supply device. The wave form diagram which showed the relationship between the input current and input voltage of the conventional DC power supply device. The circuit and control block diagram of the conventional DC power supply device. The wave form diagram which showed the relationship between the input current and input voltage of the conventional DC power supply device.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing the configuration of the DC power supply device according to the first embodiment. In FIG. 1, 1 is an AC power source, 2 is a full-wave rectifier circuit composed of four silicon diodes for full-wave rectification of the voltage of the AC power source 1, and 3 is connected at one end to the positive output side of the full-wave rectifier circuit 2. DC reactor 4 for storing energy and smoothing current 4 is a smoothing unit for smoothing the DC bus voltage provided between the other end of DC reactor 3 and the negative output side of full-wave rectifier circuit 2. A capacitor 5 is a reverse current blocking diode that is provided between the other end side of the DC reactor 3 and the positive side of the smoothing capacitor 4 and prevents current from flowing backward from the smoothing capacitor 4 side to the full-wave rectifier 2.

  The backflow prevention diode 5 uses a Schottky barrier diode that performs a diode action by bringing a semiconductor into contact with a metal. This is a silicon carbide that has high thermal stability and good heat conduction, so it can operate at high temperature, has a very low reverse recovery charge, has a short reverse recovery time, and therefore has low switching loss and a low forward voltage drop. A Schottky barrier diode using is used. For example, in a silicon carbide Schottky barrier diode having a rated reverse breakdown voltage of 600 V and a rated forward current of 6 A used for power, the reverse recovery charge is about 20 nc, which is significantly smaller than that of a silicon diode PN junction diode.

  6 is a switch means provided between the other end side of the DC reactor 3 and the negative output side of the full-wave rectifier circuit 2, and switches between DC buses. 7 is an inverter and a DC brushless motor connected in parallel to the smoothing capacitor 4. (Hereinafter referred to as DCBLM) equipped with a compressor load for air conditioning, 8 is a power supply synchronization signal created from the voltage of the AC power supply 1, a current signal of the AC power supply 1, and the current rotational speed of the load obtained from the rotational speed detecting means 13 described later. Control means for controlling opening and closing of the switch means 6 based on a current bus voltage and a target rotational speed obtained from the voltage detection means 12 described later, and a voltage for detecting the voltage value of the bus voltage and transmitting it to the control means 8 with a low voltage signal The detection means 13 is a rotation speed detection means for detecting the rotation speed of the motor of the load 7 and transmitting it to the control means 8 with a low-voltage electric signal.

  FIG. 2 is a diagram showing a circuit and a configuration of a load of the DC power supply device shown in FIG. 1, and constitutes an air conditioner that compresses the refrigerant in the cooling / heating cycle together with the DC power supply device. In FIG. 2, reference numerals 21 to 26 denote IGBTs using silicon as switches of inverters for switching the DC voltage selected by the DC power supply device of FIG. 1 to generate an AC voltage. In FIG. 2, reference numerals 31 to 36 denote silicon PN junction diodes that are forward-biased when the IGBT is turned off and flow a regenerative and return current of a DCBLM compressor 27 described later. In FIG. 2, reference numeral 29 denotes a snubber capacitor that absorbs steep voltage fluctuations between the DC bus PN due to inductance between the DC power supply and the load during the IGBT switching. In FIG. 2, reference numeral 27 denotes a refrigerant for a cold cycle equipped with a three-phase DCBLM that rotates in synchronization with an AC voltage from a main circuit of a voltage-type inverter composed of IGBTs 21-26, diodes 31-36, and snubber capacitors 29 during steady operation. It is a DCBLM compressor that compresses. In FIG. 2, reference numeral 28 denotes DCBLM control means for detecting the phase voltage of the DVBLM compressor during steady operation of the compressor 27 and turning on / off the IGBTs 21 to 26 to rotate the DCBLM.

  FIG. 3 is a timing chart showing the switch operation of the IGBTs 21 to 26 and the phase voltage of the motor of the DCBLM compressor 27 of the load shown in FIG. Although details will be described later with reference to FIG. 3, A to L indicate energization intervals between timings at which the IGBTs 21 to 26 switch energization during one electrical rotation period of the DCBLM of the compressor 27.

  Next, the operation will be described. First, when the switch means 6 does not operate at all in FIG. 1, the current rectified by the 2 full-wave rectifier circuit passes through the reactor 3 and the backflow prevention diode 5 and is accumulated in the capacitor 4 and is passive full-wave. It becomes a DC power supply device by rectification. As shown in FIG. 1, the output terminal voltage of the rectifier circuit 2 is Vi1, the DC positive bus terminal voltage of the switch means 6 is Vi2, and the DC positive bus terminal voltage of the smoothing capacitor 4 is Vo. When the switch means 6 does not operate at all, when the direct current rectified by the full-wave rectifier circuit 2 is in the state of Vi2> Vo, a forward bias is applied to the diode for the backflow element, and a current flows through the diode in the forward direction. The voltage Vi2 = Vi1 + VL, and the voltage VL is an increase due to the current energy accumulated in the DC reactor 3. However, in the DC power supply device of the present invention and its load, the power supply side voltage Vi2 is not always higher than the load side voltage Vo. There is a state where the power supply voltage Vi1 decreases. Furthermore, the voltage increase due to the stored energy of the DC reactor is released to the load side and decreases. On the other hand, the voltage on the load side Vo rises due to the energy stored in the smoothing capacitor, and the power is discharged to the load 7 and lowered. Further, when the load side motor is an automobile or a motor for driving a train, there is a case where the motor generates a power generation action when the inertia of the moving means is large. In addition, there are many cases where the voltage on the load side, that is, the system side is high in an inverter that cooperates with the system as a load such as a solar battery. In such a case, there is a state where Vi2 <Vo, and when the switch means 6 does not operate at this time, the voltage on the power source side, which is the direct current rectified by the full-wave rectifier circuit 2, is small and the reverse current element diode A reverse bias is applied from the load side, and this diode prevents a current from flowing in the forward direction.

  When the power consumption of the load 7 is small and the harmonic current and power factor from the AC power source 1 are at a level that does not cause a problem, the switch means is not operated, and the inverter on the load 7 side uses pulse width modulation (PWM). The voltage is varied to control the motor speed to the target speed. In this case, since the DC power supply device does not switch, loss due to the switching means does not occur, and a diode having a wide gap energy band having a larger energy gap than silicon, such as a backflow prevention diode 5 silicon carbide semiconductor, is used in the forward direction. The DC power supply can be operated with high efficiency at light loads with low voltage and high operating rate. As semiconductors having a wide gap energy band, semiconductors of gallium arsenide and semiconductors of gallium and itride called ticker gallium are known in addition to silicon carbide. In addition, since a diode having such a wide gap energy band is used, a reverse voltage is applied, and even if a reverse current flows for a long time, the element has high thermal stability and high thermal conductivity. Even when a large amount of power is supplied from the load side, a reliable DC power supply device can be obtained.

  The switch means 6 is not operated when the load is small in this way, but the magnitude of the load is measured by measuring the motor input current and the rotational speed, or estimating the difference in the refrigerant pressure of the compressor from the opening of the on-off valve, Alternatively, the switch means 6 may not be operated by determining whether the load is equal to or less than a preset load by capturing measurable data such as the temperature of the heat exchanger connected to the refrigeration cycle from the compressor and a predictable phenomenon. Or only when the amount of electromagnetic noise exceeds the limit value, that is, when the high frequency exceeds the regulation value, it may be operated only for specific conditions such as operating the switch means. Of course, it is okay.

  Next, when the power consumption of the load 7 is large, that is, the rotation speed of the compressor is high, the high-temperature and high-pressure refrigerant discharged from the compressor 27 to the refrigeration cycle is circulated through a heat exchanger such as an air conditioner, and this entry of the low-temperature and low-pressure refrigerant is performed. The operation of the DC power supply when the output refrigerant pressure difference is large will be described. In this case, the switch means 6 performs on / off once in 50 μsec. The control means always performs repetitive control at intervals of 50 μsec, and the on / off time ratio in 50 μsec is set to pulse width modulation (PWM) in which the operation means is detected and the control means 8 sequentially controls. In FIG. 1, while the switch means 6 is on, the current flows from the AC power supply 1 through the full-wave rectifier 2 and the DC reactor 3, through the switch means 6, through the full-wave rectifier 2, and into the AC power supply 1. Can be routed. After the switch means 6 is turned on, the input current will not be interrupted for a while even if the switch means 6 is turned off thereafter. This is due to the nature of the DC reactor 3, and since the reactor has the property of continuing to flow current, the energy stored in the reactor passes through the backflow prevention diode 5 and is charged to the smoothing capacitor 4, Input current flows. Therefore, the input current continues to flow until the energy stored in the DC reactor 3 is consumed. This phenomenon is the same even when the AC reactor 20 of FIG. The energy stored in the reactor is circulated to the power supply side through the circuit of the switch means.

  If the inductance value of the DC reactor 3 is a value that allows a sufficient current to flow until the next ON after the OFF, the current from the AC power source 1 can be continuously supplied. Therefore, if the on-time of the switch means is continuously modulated, the current from the AC power source 1 can be continuously generated.

  Depending on the value of the DC reactor 3 and how to select the switch time, the switch means is usually turned on while the current continues to flow through the DC reactor 3. In this case, the reverse current blocking diode 5 is also carbonized with low reverse recovery charge. Since the silicon diode is used, the reverse recovery current flowing from the diode to the switch means is small even when the switch means 6 is turned on, and the switch loss of the diode 5 and the switch means 6 is small. . Further, since the loss is small, the heat dissipation parts of the switch means and the backflow prevention diode can be reduced.

  In this case, since it is only necessary to maintain a current of 50 μm at the maximum, the DC reactor can be reduced and the size can be reduced. The small reactor reduces the resistance of the reactor, reduces the reactor loss and reduces the size, and further increases the efficiency. If this cycle time is lengthened, the amount of charge of the reactor will increase and not only will it approach the frequency band that humans can hear, but the voltage increase rate and current increase rate per unit will increase, affecting the elements used for the DC power supply device as a whole. become. The switch period is 50 μ, and the ripple of the input current by the switch is 20 kHz. For this reason, noise caused by the current ripple generated from the reactor 3 cannot be heard by humans.

  The on-time of the switch means 6 described above is determined by the control means 8 based on the difference between the target current value not including the harmonic current and the actual current from the current signal of the AC power supply 1. . The target current value is a sinusoidal current whose effective value is the target rotational speed, the actual rotational speed obtained from the rotational speed detection means 13, and the current effective value obtained from the current bus voltage. In this way, a small and lightweight DC power supply that can extract power from the AC power supply 1 in a state where the power factor is nearly 1 and with less harmonic current, and can supply power to a load driven by a DC voltage with high efficiency. Can be obtained. If the switch is always operated at a period of 50 μ without providing a condition for not operating the switch, a substantially sinusoidal current in phase with the input voltage can be obtained. In this way, the control means 8 measures the ON time of the IGBT as the switch means from the difference between the sine wave target current synchronized with the sine wave power supply voltage and the measured value transmitted for each switch cycle. Control. When the measured value is smaller than the target value, the ON time is increased, and when the measured value is larger, the ON time is shortened.

  The amplitude of the sine wave target current may be determined from the difference between the target value of the bus voltage and the measured value of the bus voltage. When the actual bus voltage is lower than the target, the current is increased to increase the voltage. If the measured value of the bus voltage is higher than the target, the current is reduced to lower the bus voltage. This target bus voltage may be controlled according to the load supplied by the DC power supply. For example, in order to control the rotation speed of the compressor, control is applied to the difference between the target rotation speed and the measured value. In FIG. 2, the load DCBLM compressor 27 rotates in synchronization with the AC voltage obtained by switching the IGBTs 21-26. If attention is paid to the U phase in FIG. 3, an induced voltage is generated in the phase by turning off both the IGBTs 21 and 22 of the section U phase at 60 degrees of the energizing sections FG and LA in the vicinity of the DCBLM phase voltage zero cross. The timing is detected, and the control means 28 in FIG. A voltage is applied to the U phase of the on-motor in the 120-degree section BCDE, HIJK where the absolute value of the induced voltage is high, and the rotation is maintained. The same operation is performed for the other phases. In this energization method, each IGBT is switched only once per electrical cycle.

  In the above energization method, if the rotation speed of the motor is constant, the effective value of the voltage applied to the motor is uniquely determined by the bus voltage between PN. Therefore, the rotational speed of the DCBLM can be controlled by varying the applied voltage by varying the bus voltage. As described above, the bus voltage is transmitted from the control means 28 in FIG. 2 or the rotational speed detection means 13 in FIG. 1 to the control means 8 in FIG. The bus voltage is increased or decreased to obtain the target motor speed, and air conditioning control is performed. That is, the DC power supply device has a function of controlling the rotational speed. When the switch means 6 is turned on, the reactor is charged, and when the switch is turned off thereafter, the voltage increment VL stored in the reactor is increased and applied to the load side. When this increased voltage is stored in the smoothing capacitor and the switch is turned on again, it is added to the backflow blocking diode as a higher voltage, but since a semiconductor having a wide gap energy band such as silicon carbide is used, reliability is high and loss is also caused. Can be small. When the switch 6 is turned on in FIG. 1, Vi2 is almost zero and Vo is applied, so that a reverse bias is always applied to the backflow prevention diode 5.

  With such a configuration and operation, each IGBT and diode on the load side has a large switch loss and is composed of silicon with a low operating temperature, but it is on / off only once per electrical cycle, so the loss is also small, The heat dissipation structure is simple, small and light, and the generation of electromagnetic noise generated by the switch can be suppressed. Furthermore, by not switching, there is no current ripple flowing through the motor, no switch noise from the motor, high frequency iron loss of the motor is significantly reduced, and load efficiency is increased.

  In the present embodiment, the load side can be made more efficient together with the higher efficiency of the DC power supply device, so that the cooling / air-conditioning apparatus itself can be made more efficient. In addition, by reducing the size of the heat dissipation structure on the side of the DC power supply and the reactor, the size of the heat dissipation structure on the load side can also be reduced, so that the cooling / heating air conditioner itself, for example, the outdoor unit can be downsized.

  In addition, the noise on the DC power supply side can be reduced and the noise on the load side motor can be reduced. Furthermore, since the reactor and the mechanical parts used for soundproofing the motor, such as strong mechanical parts, urethane and other sound absorbing materials and soundproofing structures can be eliminated or simplified, the air conditioner can be further reduced in size and weight. In addition, since the noise is low, the effect is remarkably high in a cold air-conditioning apparatus used indoors.

  In addition, by reducing the electromagnetic noise on the DC power supply side and the electromagnetic noise on the load side, the air conditioner itself can reduce the noise. In addition, the power line filter, which is currently used for noise countermeasures, can be made smaller, and an electromagnetic shield is not required, so the air conditioner can be made smaller and lighter. Further, the downsizing of the line filter reduces the loss of the common choke mode coil wound around the reciprocating wire, reduces heat generation, further simplifies the structure, and improves the efficiency of the cooling / heating air conditioner.

  Such downsizing and simplification of the structure further reduce the cost of load side devices such as a cold air conditioner by reducing the number of soundproofing and noise countermeasure components. Further, in the present embodiment, the above effect can be obtained by using only one silicon carbide diode, which is more expensive than a silicon diode, so that a DC power supply device and a cold air conditioner that are very cost effective can be obtained. It is done.

  FIG. 4 is a block diagram showing the configuration of another example DC power supply apparatus. In FIG. 4, 40 is a direct current power supply by series-parallel connection of solar cells, 3 is connected to the positive output side of 40 direct current power supply, one end side is connected to a direct current reactor for storing energy and smoothing current, 4 is a direct current reactor 3 A smoothing capacitor 5 for smoothing the DC bus voltage provided between the other end side of the DC power supply 40 and the negative output side of the DC power supply 40 is provided between the other end side of the DC reactor 3 and the positive side of the smoothing capacitor 4. And a reverse current blocking diode that prevents current from flowing backward from the smoothing capacitor 4 side to the DC power supply 40.

  The reverse current prevention diode has high thermal stability and good heat conduction, so it can be operated at high temperature, and the reverse recovery charge is very small and the reverse recovery time is short, so the switching loss is small and the forward voltage drop is also reduced. A Schottky barrier diode using a small amount of silicon carbide is used. A silicon carbide Schottky barrier diode with a rated reverse breakdown voltage of 600 V and a rated forward current of 6 A currently used for power has a reverse recovery charge of about 20 nc, which is significantly smaller than that of a silicon diode PN junction diode.

  6 is a switch means provided between the other end of the DC reactor 3 and the negative output side of the full-wave rectifier circuit 2 and switches between the DC buses. 7 is a DC voltage connected in parallel to the smoothing capacitor 4 to an AC voltage. A three-phase grid-connected inverter that is converted into a grid and connected to the grid, 8 is a power supply synchronization signal created from the voltage of the AC power supply 1, a current signal of the AC power supply 1, and a current bus voltage obtained from the voltage detection means 12 described later. Control means 12 for controlling opening / closing of the switch means 6, and voltage detection means 12 for detecting the voltage value of the bus voltage and transmitting it to the control means 8 by a low voltage signal. Reference numeral 41 denotes voltage detection means for transmitting the voltage of the DC power source to the control means 8.

  Next, the operation will be described. The switch means 6 performs a switching operation in which on / off is repeated once within 50 μsec. In FIG. 4, while the switch means 6 is on, there is a current path that flows from the DC power supply 40 through the DC reactor 3, through the switch means 6, through the full-wave rectifier 2, and to the AC power supply 1. If the switch means 6 is on, even if the switch means 6 is subsequently turned off, the input current will not be interrupted for a while. This is due to the nature of the DC reactor 3, and since the reactor has the property of continuing to flow current, the energy stored in the reactor passes through the backflow prevention diode 5 and is charged to the smoothing capacitor 4, Input current flows. Accordingly, the input current continues to flow until the energy stored in the DC reactor 3 is consumed, and the energy of the DC power source is transmitted to the electrolytic capacitor 4. The control means 8 determines an on time and an off time of 25 μsec so that the voltage of the voltage detection means 12 becomes a constant voltage. When the load amount is large and the detection voltage of the voltage detection means 12 is lower than the target voltage, the on time of the switch means 6 becomes longer, and conversely, when the load voltage is lower than the target voltage, the on time becomes shorter.

  The load amount, that is, the amount of power regenerated in the system is determined by the control means 8 based on the voltage of the DC power source 40, that is, the solar cell detected by the voltage detecting means 41, and the load amount of the load 7 is determined by analogy with the maximum power generation amount of the solar cell. Send generated power to the grid. The solar cell has a voltage / current point that can obtain the maximum power that can be output with respect to a certain amount of solar radiation, but in this embodiment, the high power point tracking that always follows the load amount that can obtain the maximum power according to the solar radiation situation. Take control. This follow-up control is a method of setting the output by searching for the point at which the product of the voltage and current becomes the maximum at that time when the light intensity changes, with the output side power slightly increased and decreased.

  Normally, the switch means is turned on while the current continues to flow through the DC reactor 3 depending on the value of the DC reactor 3 and how to select the switch time. In this case as well, the reverse current blocking diode 5 is a silicon carbide diode with little reverse recovery charge. Even when the switch 6 is turned on, the reverse recovery current flowing from the diode to the switch means is small, the switch loss of the diode 5 and the switch means 6 is small, and a DC power supply device with a small loss can be obtained even when the switch cycle is 25ψμsec. Further, since the loss is small, the heat radiation of the switch means 6 and the backflow blocking diode 5 can be reduced.

  In addition, since it is only necessary to maintain a current of a maximum of 25 μm, the maximum size and maximum DC reactor can be made very small and light in the DC power supply device. Lightening eliminates mounting restrictions and reduces the number of workers during construction. In addition, since the reactor is small, the resistance of the reactor is reduced, and loss and heat generation in the reactor are reduced, so that not only miniaturization but also higher efficiency can be achieved. Further, the switch cycle is 25 μ, and the ripple of the input current by the switch is 40 kHz. Therefore, noise caused by current ripple generated from the reactor 3 cannot be heard at all. Therefore, a DC power supply device with less noise can be obtained. In a grid-connected inverter for residential use installed indoors, the noise of the loudest DC reactor can be made an inaudible frequency, and the effect is particularly high. Furthermore, there is a synergistic effect that the weight of the reactor, which has been further increased to increase the strength as a noise countermeasure, is reduced and the weight of the entire apparatus is reduced.

  Further, by using silicon carbide having a low reverse recovery current for the backflow prevention diode 5, the amount of electromagnetic noise generated can be significantly reduced even if the switching cycle is shortened to 25 μsec. Therefore, it is particularly effective for a commercial grid-connected inverter that requires a large noise filter between the DC power supply and the reactor as a countermeasure against electromagnetic noise. In the case of an AC power supply, the condition that leads to a reverse flow in the present invention is that a ripple occurs depending on smoothness when the AC power supply is rectified, and a reverse bias corresponding to the power supply cycle is applied. In the case of a DC power supply, the load is constant, but the voltage of the DC power supply drops rapidly, the solar battery reduces solar radiation, the storage battery reduces the remaining battery capacity, and so on. In the case of an inverter + motor in which the load side is in the regeneration mode, a reverse flow occurs when the bus voltage suddenly increases due to the occurrence of regeneration on the load side. As for the loss of the backflow prevention diode, when the backflow prevention diode is forward-biased and a current flows, a forward voltage is generated at both ends of the normal diode, and the product of this voltage and the forward current becomes the loss of the diode.

  FIG. 5 is a three-side view of the structure of the room air conditioner outdoor unit when the power unit described above is used as an inverter device for variable speed operation of the compressor and blower of the room air conditioner outdoor unit and its motor to the load. 5, 51 is a front view of the outdoor unit, 52 is a top view of the outdoor unit, and 53 is a side view of the outdoor unit. Reference numeral 54 denotes a compressor that compresses the refrigerant, 55 a blower, 56 a heat exchanger, and 57 a circuit including a reactor of the DC power supply device, a power supply device, and an inverter device.

  The circuit 57 including the reactor of the DC power supply device, the power supply device, and the inverter device operates as a cold air conditioner using refrigerant by driving the compressor 54 and the blower 55.

  A heat exchanger 56 is arranged in the air path by the blower 55 to perform heat exchange. Since the reactor has been reduced in size and weight, the reactor can be mounted on the circuit board. Furthermore, the circuit and the reactor and the compressor can be arranged on the lower surface thereof so as not to obstruct the air path of the heat exchanger 56 and the blower 55. The circuit 57 is mounted with the switching means of the DC power supply device, the backflow prevention diode, and the switching means of the inverter device described above. Further, the switch means and the heat radiation fin of the backflow prevention diode are mounted. The circuit is also equipped with a choke coil, which is a noise countermeasure component, to prevent electromagnetic noise on the power line.

  As described above, a DC power supply circuit and an inverter are used, and the arrangement of each component of the outdoor unit is made the arrangement of FIG. 5 that can make the circuit and the reactor common, and the air path of the heat exchanger 56 and the blower 55 can be simplified. Thus, the width of the outdoor unit can be reduced. Therefore, a small and light room air conditioner outdoor unit that can be installed in a narrow space such as a veranda can be obtained. In addition, since a heavy compressor, reactor, and circuit can be arranged on the bottom surface, in addition to being light, the center of gravity is low, the balance when lifting is good, and a room air conditioner that feels lighter than before can be obtained. Furthermore, the degree of freedom of arrangement of the heat exchanger is increased, so that the side of the fan is entirely covered with the heat exchanger, or more heat-efficient arrangement such as taking in air from the upper part and passing through the heat exchanger can be freely selected.

  In the above description, a three-phase motor is used as a load. However, the same effect can be obtained even when the number of other phases is also a motor. Although DCBLM is used as a load, the same effect can be obtained with other motors such as an induction motor and a reluctance motor. Moreover, although the solar cell was used for DC power supply, the same effect is acquired even if it uses batteries, such as a lead livestock battery. In addition, a grid-connected inverter is used for the load, but the axle or steering drive motor for trains, passenger cars, commercial vehicles, etc. whose weight affects fuel and electricity costs and noise affects passenger comfort Even if used, the same high effect can be obtained.

  According to the present invention, it is possible to obtain a DC power supply apparatus and a load that are inexpensive, have high conversion efficiency, are small, light, have low noise, and have low electromagnetic noise.

  In addition, according to the present invention, since a wide gap semiconductor diode with small on loss, switch loss, and recovery current is used for the backflow prevention diode, a DC power supply device with high efficiency, small size, light weight, low noise, and low electromagnetic noise Is obtained.

  In addition, according to the present invention, since a silicon carbide semiconductor diode with low on loss, switch loss, recovery current and low raw material is used for the backflow prevention diode, it is inexpensive, highly efficient, small, lightweight, low noise, A DC power supply device with low electromagnetic noise can be obtained.

  In addition, according to the present invention, a Schottky diode with a small on loss, switch loss, and recovery current, which is simple and inexpensive, is used for the backflow prevention diode, so it is inexpensive, highly efficient, small, lightweight, and low noise. A DC power supply device with small electromagnetic noise can be obtained.

  Further, according to the present invention, the use of a motor as a load provides a DC power supply device that can be driven with low cost, high efficiency, small size, light weight, and low noise. By using a compressor motor for the load, it is possible to obtain a DC power supply device that can drive the compressor at low cost, high efficiency, small size, light weight and low noise. By using a blower motor for the load, a direct current power supply device that can be driven with low cost, high efficiency, small size, light weight and low noise can be obtained. By using a DC brushless motor as a load, a DC power supply device that can drive the brushless motor at low cost, high efficiency, small size, light weight and low noise can be obtained.

  In addition, according to the present invention, by setting the switch frequency to an inaudible frequency, a low-cost, high-efficiency, small-sized, light-weight and low-noise DC power supply device and its load can be obtained. Further, an inexpensive, highly efficient, compact, lightweight, and low noise DC power supply device can be obtained.

  In addition, according to the present invention, a solar battery is used as a direct current power source and combined with the direct current power supply device, so that it is inexpensive, highly efficient, small, lightweight, low noise, and low in electromagnetic noise and solar power. A photovoltaic system is obtained. By using a livestock battery as a DC power source and combining it with the above-described DC power source device, a DC power source device and a power storage system that are inexpensive, highly efficient, small, light, low noise, and low in electromagnetic noise can be obtained.

  In addition, according to the present invention, a DC power supply using a grid-connected inverter as a load is combined with a DC power supply, so that it is inexpensive, highly efficient, small, lightweight, low noise, and has low electromagnetic noise. A system is obtained. In addition, according to the present invention, a drive motor of equipment used for moving means of people and things is used as a load and combined with a DC power supply device, so that it is inexpensive, highly efficient, compact, lightweight, low noise, electromagnetic noise A small DC power supply device and mobile equipment can be obtained.

  The present invention comprises a rectifier circuit for rectifying alternating current from an alternating current power supply or a smoothing capacitor for smoothing a direct current voltage between direct current buses supplied from a direct current power supply, a switch means disposed on the power supply side of the smoothing capacitor, and a switch means. A reactor that is arranged on the power supply side and can store current energy, and a carbonization that is arranged between the smoothing capacitor and the switch means to prevent backflow from the smoothing capacitor to the power supply side, and forward and reverse voltages are applied when the switch means is off. Since a backflow prevention diode having a wide gap energy band such as a silicon semiconductor is provided, a small and high-performance device can be obtained.

  According to the present invention, the switch means is not operated when the load connected in parallel to the smoothing capacitor is light, so that a device with little loss is obtained.

  In the present invention, since the backflow prevention diode is a Schottky junction diode, an inexpensive device having a simple structure can be obtained.

  In the present invention, the load connected in parallel to the smoothing capacitor is a DC brushless motor, and the speed control of the brushless motor is performed by varying the DC voltage, so that the motor can be driven efficiently.

  In the present invention, since the switch frequency of the switch means is set to an inaudible frequency, a low noise device can be obtained.

  According to the present invention, the switch means repeats a cycle having ON and OFF that can be changed in time within a certain time, and this cycle frequency is set to a non-audible frequency, so that an apparatus having a quiet sound and high efficiency can be obtained.

  In the present invention, since a power supply having a large voltage fluctuation such as a solar battery or a storage battery is used as the DC power supply, a highly reliable and efficient device can be obtained even if the power supply voltage changes depending on the operation state.

  In the present invention, since the semiconductor component other than the backflow prevention diode to be used is a silicon semiconductor, an inexpensive device can be obtained.

  In the present invention, the load connected in parallel to the smoothing capacitor is a compressor motor in which the current flowing through the load fluctuates, a drive motor for equipment used for moving means of people and things, a fan motor, or a grid interconnection inverter. Yes, even if there is a reverse flow from the load side to the power source side, a highly reliable and efficient device can be obtained.

  DESCRIPTION OF SYMBOLS 1 AC power supply, 2 Full wave rectifier circuit, 3 DC reactor, 4 Capacitor, 5 Backflow prevention diode, 6 Switch means, 7 Load, 8 Control means, 9 Memory | storage means, 10 Load amount detection means, 11 Selection means, 12 Voltage detection Means, 13 rotation speed detecting means, 14 voltage setting device, 15 voltage control amplifier, 16 multiplier, 17 comparator, 18 base drive circuit, 19 power supply side filter, 20 AC reactor, 21-26 IGBT, 27 DCBLM compressor, 28 control means, 29 snubber capacitor, 31-36 diode, 40 DC power supply, 41 voltage detection means, 51 front view of room air conditioner outdoor unit, 52 top view of room air conditioner outdoor unit, 53 side view of room air conditioner outdoor unit, 54 Compressor, 55 Blower, 56 Heat exchangers, 57 reactors and circuits.

Claims (6)

A smoothing capacitor that smoothes a DC voltage between DC buses supplied from a rectifier circuit or DC power supply that rectifies AC from an AC power supply;
Switch means arranged on the power supply side from the smoothing capacitor;
A reactor arranged on the power supply side from the switch means and capable of storing current energy;
A backflow prevention diode which is disposed between the smoothing capacitor and the switch means to prevent a backflow from the smoothing capacitor to the power supply side and to which a forward voltage and a reverse voltage are applied when the switch means is off;
Control means for controlling the rotational speed of the DC motor to a target rotational speed by opening and closing the switch means;
An inverter connected in parallel to the smoothing capacitor and switched to synchronize with the DC motor;
A compressor of an air conditioner outdoor unit that is a load of the DC motor,
The blocking diode using wide-gap semiconductor, Rutotomoni a silicon semiconductor semiconductor components other than the blocking diode, and at least one said reactor of the smoothing capacitor or said switching means or said back-flow preventing diode or the inverter It is configured to be arranged on the same plane ,
The control means turns off the switch means if the rotation speed controlled by the DC motor is equal to or less than a preset rotation speed, and the switch means at regular intervals if the rotation speed is equal to or greater than a preset rotation speed. A room air conditioner characterized by turning on. The room air conditioner according to claim 1, wherein a load connected in parallel to the smoothing capacitor is a DC brushless motor, and speed control of the brushless motor is performed by varying the DC voltage. The room air conditioner according to claim 1 or 2, wherein a switch frequency of the switch means is an inaudible frequency. The room air conditioner according to claim 3, wherein the switch means repeats a cycle having ON and OFF that can change the time setting within a predetermined time and sets the cycle frequency to an inaudible frequency. The room air conditioner according to any one of claims 1 to 4, wherein a power source having a voltage fluctuation such as a solar battery or a storage battery is used as the DC power source. The room air conditioner according to any one of claims 1 to 5, wherein the backflow prevention diode is a Schottky junction diode.

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