JP5259941B2 - Inverter device and air conditioner - Google Patents

Description

  The present invention relates to an inverter device used in, for example, an air conditioner.

Conventionally, in an inverter device that converts DC power to AC power and outputs it to a load or the like, the input DC voltage is passed through a filter having a predetermined time constant, and the difference between the value after passing through this filter and the instantaneous value of the input DC voltage There is known a technique for detecting an instantaneous power failure when the value becomes equal to or greater than a predetermined value (for example, see Patent Document 1).
JP 2000-253673 A

However, normally, when detecting the DC voltage as described above, since the voltage is detected in an insulated state via a photocoupler or the like, a detection delay due to the photocoupler occurs, and the DC voltage is detected in real time. There was a problem that the voltage could not be detected.
Moreover, in the conventional inverter apparatus mentioned above, there existed a problem that the detection timing of an instantaneous power failure could not be changed according to the use condition etc. of an inverter apparatus.
In particular, in an air conditioner, due to the above problems, there is a concern that electronic components may be damaged or operation may be unstable at the timing when the power is restored before the operation is stopped.

The present invention has been made to solve the above problem, and an object thereof is to provide an inverter device and an air conditioner that can reduce the detection delay of a DC voltage.
An object of this invention is to provide the inverter apparatus and air conditioner which can adjust the detection timing of an instantaneous power failure according to a use condition.

In order to solve the above problems, the present invention employs the following means.
The present invention includes an inverter means, the DC voltage input to said inverter means is inputted not through the insulating element, the difference between the instantaneous value and the average value of the input direct current voltage is equal to or greater than a predetermined threshold value A first microcomputer for detecting an instantaneous power failure, and an inverter device in which the first microcomputer and the inverter means are connected to a common ground.

According to such a configuration, the DC voltage input to the inverter means is monitored by the first microcomputer, and the difference between the instantaneous value and the average value of the DC voltage is equal to or greater than a predetermined threshold value. An instantaneous power failure will be detected. In this case, since the first microcomputer and the inverter means are connected to a common ground, the direct current voltage input to the inverter means is directly applied to the first microcomputer without interposing a photocoupler or the like. It can be detected by a computer.

In the inverter device, the first microcomputer has a low-pass filter to which the DC voltage is input, and uses an output value of the low-pass filter as the average value, and a current value output from the inverter means. Accordingly, at least one of the time constant of the low-pass filter and the predetermined threshold value may be changed.

According to such a configuration, the DC voltage input to the inverter means is monitored by the first microcomputer , and when the difference between the instantaneous value and the average value of the DC voltage is equal to or greater than the predetermined threshold, A power outage will be detected. In this case, since the DC voltage that has passed through the low-pass filter is used as the average value of the DC voltage, the average value of the DC voltage can be obtained with a simple configuration. Furthermore, since at least one of the time constant of the low-pass filter and the predetermined threshold value is changed according to the current value output from the inverter means, an instantaneous power failure is caused at a timing according to the usage status of the inverter means. Can be detected. Thus, the operation can be stopped before the air conditioner becomes unstable in operation, and the electronic component or the system of the air conditioner can be protected.

  The inverter device includes a relay provided on a power supply line for supplying DC power to the inverter means, and the first microcomputer is configured to calculate an instantaneous value and an average value of a DC voltage input to the inverter means. When the difference between the inverter control means for stopping the inverter means and the instantaneous value and the average value of the DC voltage input to the inverter means exceeds a predetermined threshold when the difference becomes a predetermined threshold value or more. Relay control means for opening the relay after a predetermined first time has elapsed may be provided.
  In the inverter apparatus, the relay control means counts a third time that is set longer than the first time when the relay is opened due to the detection of the instantaneous power failure. And when the relay is opened due to the detection of the instantaneous power failure, the DC voltage input to the inverter means is equal to or higher than the voltage value when the instantaneous power failure is detected. Second time measuring means for measuring a second time that is longer than 1 time and shorter than the third time, and the third time measuring means or the second time measuring means counts up. In this case, the relay may be closed.
  The inverter device includes an active filter circuit provided closer to the inverter means than the relay in the power supply line, and a second microcomputer that controls the active filter circuit, and the first microcomputer When an instantaneous power failure is detected, a signal to that effect is output to the second microcomputer, and the second microcomputer receives a signal indicating that an instantaneous power failure has been detected from the first microcomputer. When the signal is input, the active filter circuit may be stopped after the first time has elapsed from the input of the signal.
  In the inverter device, the first microcomputer and the second microcomputer may be connected via a photocoupler.

The inverter device of the present invention is suitable for use in an air conditioner.
Moreover, the above-mentioned various configurations can be used in combination within a possible range.

According to the present invention, there is an effect that the detection delay of the DC voltage can be reduced.
ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the detection timing of an instantaneous power failure can be adjusted according to the use condition of an inverter apparatus, and the operating condition of an air conditioner.

An embodiment of an inverter device according to the present invention will be described below with reference to the drawings.
FIG. 1 is a circuit block diagram showing a schematic configuration of the inverter device according to the present embodiment.
As shown in FIG. 1, an inverter device 1 according to this embodiment includes an AC power source 2, a rectifier circuit 3 that converts AC power output from the AC power source 2 into DC power, and DC power output from the rectifier circuit 3. An active filter circuit 4 that converts the DC power to a desired voltage value and improves the power factor, and an inverter circuit 5 that converts the DC power output from the active filter circuit 4 to AC power and outputs the AC power to the load 6 are mainly used. It is prepared as a simple configuration.

  A noise filter 7 for removing noise components is provided between the AC power supply 2 and the rectifier circuit 3. A relay 8 is inserted in the power supply line L1 between the rectifier circuit 3 and the active filter circuit 4. A resistor 9 is connected to the relay 8 in parallel. A reactor 10 is inserted in the power supply line L1 between the relay 8 and the active filter circuit 4. A capacitor 11 is connected in parallel between the active filter circuit 4 and the inverter circuit 5. Specifically, the positive side of the capacitor 11 is on the power supply line L1 between the active filter circuit 4 and the inverter circuit 5, and the ground line L2 between the active filter circuit 4 and the inverter circuit 5 is on the ground line L2 between the active filter circuit 4 and the inverter circuit 5. The negative side is connected.

  The active filter circuit 4 includes, for example, a switching circuit 12 and a diode 13. The switching circuit 12 is connected to the capacitor 11 in parallel. That is, one end of the switching circuit 12 is connected to the power supply line L1, and the other end is connected to the ground line L2. The switching circuit 12 includes, for example, switching elements such as FETs and IGBTs. The diode 13 is inserted in the power supply line L <b> 1 between the switching circuit 12 and the capacitor 11. In the power supply line L1, the anode terminal of the diode 13 is connected to the switching circuit 12 side, and the cathode terminal of the diode 13 is connected to the capacitor 11 side.

  The active filter circuit 4, and the reactor 10 and the capacitor 11 described above function as a boost chopper. Specifically, when the switching circuit 12 is in an on state, a direct current flowing through the power supply line L1 flows to the ground line L2 via the reactor 10 and the switching circuit 12, whereby energy is stored in the reactor 10. In this state, when the switching circuit 12 is turned off, the energy stored in the reactor 10 flows to the capacitor 11 through the diode 13 as a current. In this manner, the switching circuit 12 is repeatedly turned on and off at a predetermined duty ratio, whereby the voltage across the capacitor 11 can be controlled to a desired voltage value, that is, the input voltage of the inverter circuit 5 can be controlled. The active filter circuit 4 performs the voltage control and also has a power factor control function.

The inverter device 1 includes a first microcomputer (control means) 20 that controls the inverter circuit 5. The first microcomputer (hereinafter referred to as “first microcomputer”) 20 has an instantaneous power failure detection function for detecting an instantaneous power failure or the like of the AC power supply 2. The ground (GND) terminal of the first microcomputer 20 is connected to the ground line L <b> 2 of the inverter circuit 5. That is, the first microcomputer 20 and the inverter circuit 5 are connected to a common ground. A power line L1 between the active filter circuit 4 and the inverter circuit 5 is indirectly connected to one input terminal of the first microcomputer 20. Specifically, the voltage of the power supply line L2 is divided by a voltage dividing circuit (not shown) to be within the allowable voltage range of the first microcomputer 20 and then input to the one input terminal. It has become. As a result, the first microcomputer 20 can directly detect the DC voltage Vin input to the inverter circuit 5 without using an insulating element such as a photocoupler.
Further, the output side of the inverter circuit 5 is provided with a current sensor 14 for detecting the output current Iout of the inverter circuit 5, in other words, the current Iout flowing into the load 6, and the detected value of the current sensor 14 is The signal is input to the other input terminal of the first microcomputer 20.

The first microcomputer 20 is connected to a second microcomputer (hereinafter referred to as “second microcomputer”) 21 via a photocoupler 22. As a result, the first microcomputer 20 and the second microcomputer 21 can transmit and receive information while being insulated.
For example, the second microcomputer 21 controls the above-described active filter circuit 4 and the like.

In the inverter device 1 having such a configuration, the inverter circuit 5 is driven by the first microcomputer 20, and the active filter circuit 4 is driven by the second microcomputer 21.
The AC power from the AC power supply 2 is converted into DC power by the rectifier circuit 3 after the noise component is removed by the noise filter 7 and input to the active filter circuit 4 via the relay 8 and the reactor 10. Due to the action of the active filter circuit 4, the DC power input to the active filter circuit 4 is converted into a predetermined voltage value and a predetermined power factor and input to the inverter circuit 5. In the inverter circuit 5, the DC power is converted into AC power having a desired frequency and a predetermined current value, and supplied to a load 6 such as a motor.
On the other hand, the DC voltage Vin (hereinafter simply referred to as “DC voltage Vin”) input to the inverter circuit 5 and the output current Iout (hereinafter simply referred to as “output current Iout”) of the inverter circuit 5 are first. Are detected by the microcomputer 20, and an instantaneous power failure or the like of the AC power supply 2 is detected based on these values.

Hereinafter, the instantaneous power failure detection function realized by the first microcomputer 20 according to the present embodiment will be described.
FIG. 2 is a functional block diagram of the first microcomputer 20.
The first microcomputer 20 includes a voltage detection unit 31 that detects an instantaneous value of the DC voltage Vin, a low-pass filter 32 provided to obtain an average value of the DC voltage Vin, and the DC voltage Vin detected by the voltage detection unit 31. According to the instantaneous power failure detection unit 33 that detects the instantaneous power failure when the difference between the instantaneous value and the output value of the low-pass filter 32, in other words, the average value of the DC voltage Vin is equal to or greater than a predetermined threshold ΔV, and the output current Iout. , A condition switching unit 34 for switching the time constant τ of the low-pass filter 32 and the threshold ΔV used by the instantaneous power failure detection unit 33, an inverter control unit 35 for controlling the inverter circuit 5, and a signal output unit for outputting a signal to the second microcomputer 21 36, a relay control unit 37 for controlling the relay 8, and the like.

  The condition switching unit 34 includes a condition setting table in which the output current Iout, the time constant τ, and the threshold value ΔV are associated with each other. FIG. 3 shows an example of the condition setting table held by the condition switching unit 34. In the present embodiment, when the output current Iout of the inverter circuit 5 is less than a predetermined threshold value Iref (for example, 500 mA), the time constant τ of the low-pass filter 32 is 30 sec, and the threshold value ΔV used by the instantaneous power failure detection unit 33 is When the output current Iout is greater than or equal to a predetermined threshold value Iref, the time constant τ is set to 0.1 sec and the threshold value ΔV is set to 50V. These specific values are merely examples, and can be set as appropriate according to the usage status of the inverter device 1. Further, the time constant τ and the threshold value ΔV may be set in multiple stages instead of two stages.

  The relay control unit 37 has three timers (not shown) that time different times Td1, Td2, and Td3 (here, Td1 <Td2 <Td3). The driving timing of this timer will be described later.

  A case where an instantaneous power failure occurs during the operation of the inverter device 1 in the first microcomputer 20 will be described with reference to FIG. Here, it is assumed that the time constant τ of the low-pass filter 32 is set to 0.1 sec, and the threshold value ΔV used by the instantaneous power failure detection unit 33 is set to 50V.

  For example, when an instantaneous power failure occurs at time T1 in FIG. 4 (see A in FIG. 4), the instantaneous value of the DC voltage Vin detected by the voltage detector 31 gradually decreases (see B in FIG. 4). Accordingly, the output of the low-pass filter 32 gradually decreases (see C in FIG. 4). When the difference between the instantaneous value of the DC voltage Vin and the output value of the low-pass filter 32 becomes equal to or greater than the threshold ΔV (= 50 V) at time T2 in FIG. 4, the instantaneous power failure detection unit 33 detects the instantaneous power failure, A notification signal indicating that is output to the inverter control unit 35, the signal output unit 36, and the relay control unit 37.

When the notification signal is input, the inverter control unit 35 quickly stops the inverter circuit 5 (see D in FIG. 4). When the notification signal is input, the signal output unit 36 outputs the notification signal to the second microcomputer 21 via the photocoupler 22 (see FIG. 1). When the notification signal is input, the second microcomputer 21 stops the active filter circuit 4 after a predetermined time Td1 has elapsed (see E in FIG. 4).
When the notification signal is input, the relay control unit 37 turns off the relay 8 after a predetermined time Td1 has elapsed from the input (see F of FIG. 4), and starts a timer for measuring the predetermined time Td3 (see FIG. 4). H).

  Subsequently, at the time T3 in FIG. 4, when the instantaneous power failure is eliminated (see A in FIG. 4), the instantaneous value of the DC voltage Vin detected by the voltage detection unit 31 gradually increases (see B in FIG. 4). Then, at time T4 in FIG. 4, when the instantaneous value of the DC voltage Vin becomes equal to or higher than the instantaneous value Vref when the instantaneous power failure is detected, the relay control unit 37 starts a timer that counts the predetermined time Td2 ( (See G in FIG. 4). Thereafter, when one of the timers counts up at time T5, the relay control unit 37 forcibly turns on the relay 8 (see F in FIG. 4). In the present embodiment, a case is shown in which a timer that counts the predetermined time Td2 counts up. When it is detected that the relay 8 is turned on in this manner, the driving of the inverter circuit 5 by the inverter control unit 35 described above is resumed and the driving of the active filter circuit 4 by the second microcomputer 21 is resumed. (Not shown).

Next, with reference to FIG. 5, the control contents of the first microcomputer 20 when the user turns off the main power switch when the operation of the inverter device 1 is stopped and immediately after the main power switch is turned on are turned on again. explain.
In this case, since the inverter device 1 has not started operation, the output current Iout of the inverter circuit 5 becomes zero. Therefore, the time constant τ of the low-pass filter 32 is set to 30 sec, and the threshold value ΔV used by the instantaneous power failure detection unit 33 is set to 70 V (see FIG. 3).

  First, when the main power supply is turned on at time T1 in FIG. 5 (see A in FIG. 5), the instantaneous value of the DC voltage Vin detected by the voltage detection unit 31 rapidly increases (see B in FIG. 5). Along with this, the output of the low-pass filter 32 gradually increases (see C in FIG. 5). When the output value of the low-pass filter 32 becomes equal to or higher than a preset start threshold value at time T2 in FIG. 5, the relay control unit 35 starts a timer that counts the predetermined time Td3, and at time T3, this timer Counts up, the relay 8 is turned on (see D in FIG. 5).

Subsequently, when the main power supply is turned off at time T4 in FIG. 5 (see A in FIG. 5), the instantaneous value of the DC voltage Vin detected by the voltage detecting unit 31 gradually decreases (see B in FIG. 5). Accordingly, the output of the low-pass filter 32 gradually decreases (see C in FIG. 5).
At time T5, when the difference between the instantaneous value of the DC voltage Vin and the output value of the low-pass filter 32 becomes equal to or greater than the threshold value ΔV (= 70V), the instantaneous power failure detection unit 33 detects the instantaneous power failure and indicates that fact. The notification signal is output to the relay control unit 37.

  When the notification signal is input, the relay control unit 37 turns off the relay 8 after a predetermined time Td1 has elapsed from the input (see D in FIG. 5) and starts a timer for measuring the predetermined time Td3 (not shown). .

  Subsequently, when the main power supply is turned on again at time T6 in FIG. 5 (see A in FIG. 5), the instantaneous value of the DC voltage Vin detected by the voltage detection unit 31 gradually increases (B in FIG. 5). reference). Then, at time T7, when the instantaneous value of the DC voltage Vin becomes equal to or higher than the instantaneous value Vref when the instantaneous power failure is detected, the relay control unit 37 starts a timer for measuring the predetermined time Td2 (FIG. 5). E). Thereafter, when one of the timers counts up at time T7, the relay control unit 37 forcibly turns on the relay 8 (see D in FIG. 5). FIG. 5 shows the case where the timer that counts the predetermined time T2 has counted up.

  When it is detected that the relay 8 is turned on in this way, the inverter circuit 5 is started to be driven by the inverter control unit 35 and the active microcomputer 4 is started to be driven by the second microcomputer 21. (Not shown).

  As described above, according to the inverter device 1 according to the present embodiment, the DC voltage Vin input to the inverter circuit 5 is monitored by the first microcomputer 20, and the instantaneous value of the DC voltage Vin is When the difference from the average value is equal to or greater than a predetermined threshold value ΔV, an instantaneous power failure is detected. In this case, since the first microcomputer 20 and the inverter circuit 5 are connected to a common ground, the direct current voltage Vin input to the inverter circuit 5 is directly connected to the first circuit without interposing a photocoupler or the like. It is possible to detect in one microcomputer 20. Thereby, the detection delay of a DC voltage can be reduced.

  Further, according to the inverter device 1 according to the present embodiment, since the output of the low-pass filter 32 is used as the average value of the DC voltage Vin, the average value of the DC voltage Vin can be obtained with a simple configuration. Furthermore, since the time constant τ of the low-pass filter 32 is changed according to the current value Iout output from the inverter circuit 5, the time constant τ is instantaneously determined according to the usage status of the inverter circuit 5, the operating status of the air conditioner, and the like. The detection timing of a power failure can be adjusted. Accordingly, it is possible to stop the operation before the air conditioner becomes unstable in operation, and it is possible to protect the electronic component or the air conditioner system. Furthermore, the system protection of the air conditioner is made without restricting the power supply situation, and the fear of component damage can be eliminated.

In the present embodiment, the time constant τ of the low-pass filter 32 and the threshold value ΔV used by the instantaneous power failure detection unit 33 are changed according to the output current Iout of the inverter circuit 5. The time constant τ and the threshold value ΔV may be changed depending on the state of FIG. In this way, by changing the time constant τ and the threshold value ΔV according to the state of the breaker, the detection timing can be made different depending on whether or not an instantaneous power failure has actually occurred. Furthermore, the system protection of the air conditioner is performed without restricting the power supply situation, and it is possible to eliminate the concern of component damage.

  In the present embodiment, both the time constant τ and the threshold value ΔV are changed, but either one may be changed.

The inverter device according to the present invention is suitable for use in, for example, a power supply device for an air conditioner, but can naturally be applied to a power supply device other than an air conditioner.
In the present embodiment, the above description has been made on the assumption that software processing is performed by a microcomputer. However, hardware such as an electronic circuit may be used instead of the microcomputer.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

1 is an electric circuit diagram showing a schematic configuration of an inverter device according to an embodiment of the present invention. It is a functional block diagram of the 1st microcomputer shown in FIG. It is the figure which showed an example of the condition setting table which a condition switching part holds. It is the timing chart which showed the contents of control of the 1st microcomputer when the instantaneous power failure occurs. It is the timing chart which showed the contents of control of the 1st microcomputer when the main power supply is repeatedly turned on and off by the user.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inverter apparatus 2 AC power supply 3 Rectifier circuit 4 Active filter circuit 5 Inverter circuit 8 Relay 14 Current sensor 20 1st microcomputer 31 Voltage detection part 32 Low pass filter 33 Instantaneous power failure detection part 34 Condition switching part 35 Inverter control part 36 Signal output Part 37 Relay control part

Claims (7)

Inverter means;
If the DC voltage input to said inverter means is inputted not through the insulating element, the difference between the instantaneous value of the input direct current voltage and the average value is equal to or greater than a predetermined threshold value, detects the instantaneous power failure A first microcomputer;
An inverter device in which the first microcomputer and the inverter means are connected to a common ground.   The first microcomputer includes a low-pass filter to which the DC voltage is input, and uses an output value of the low-pass filter as the average value, and the low-pass filter according to a current value output from the inverter means. The inverter device according to claim 1, wherein at least one of a time constant of a filter and the predetermined threshold value is changed.   Having a relay provided on a power line for supplying DC power to the inverter means;
  The first microcomputer is:
  Inverter control means for stopping the inverter means when the difference between the instantaneous value and the average value of the DC voltage input to the inverter means exceeds a predetermined threshold value;
  Relay control means for opening the relay after a predetermined first time has elapsed since the difference between the instantaneous value and the average value of the DC voltage input to the inverter means exceeds a predetermined threshold;
The inverter apparatus of Claim 1 or Claim 2 which comprises these.   The relay control means includes
  A third timing means for timing a third time set longer than the first time when the relay is opened due to the detection of the instantaneous power failure;
  When the relay is opened due to the detection of the instantaneous power failure, the first time when the DC voltage input to the inverter means becomes equal to or higher than the voltage value when the instantaneous power failure is detected. A second timing means for timing a second time that is longer than the third time and shorter than the third time.
With
  4. The inverter device according to claim 3, wherein the relay is closed when the third timing means or the second timing means counts up.   In the power supply line, an active filter circuit provided closer to the inverter means than the relay;
  A second microcomputer for controlling the active filter circuit;
Have
  When the first microcomputer detects an instantaneous power failure, it outputs a signal to that effect to the second microcomputer,
  When the second microcomputer receives a signal indicating that an instantaneous power failure has been detected from the first microcomputer, the second microcomputer stops the active filter circuit after a first time has elapsed since the input of the signal. The inverter device according to claim 3 or claim 4 to be performed.   The inverter apparatus according to claim 5, wherein the first microcomputer and the second microcomputer are connected via a photocoupler. An air conditioner provided with the inverter apparatus in any one of Claims 1-6 .

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