JP2013135516A - Electric power conversion system and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve miniaturization of an apparatus.SOLUTION: The electric power conversion system 1 includes a converter device 2 and a converter control device 3. The converter device 2 includes a rectification circuit 5, a first switching circuit 10a, a second switching circuit 10b, and a smoothing capacitor 12. The first switching circuit 10a includes an inductor 6a, a diode 7a, and a switching element 8a. The second switching circuit 10b includes an inductor 6b, a diode 7b, and a switching element 8b. The converter control device 3 acquires a parameter of a motor current used in the motor control device 20 as input information and determines whether or not the switching elements 8a and 8b are operated on the basis of the acquired input information.

Description

  The present invention relates to a power conversion device and an air conditioner including the same.

  Conventionally, an apparatus disclosed in Patent Document 1 is known as a power conversion apparatus. The power conversion device disclosed in Patent Document 1 is a converter power supply device that converts AC power into DC power, and is composed of a basic switching circuit and an additional switching circuit for the purpose of reducing harmonic components and improving power factor. It has two switching circuits. When the load is small, only the basic switching circuit is operated, and when the load is large, both the basic switching circuit and the additional switching circuit are operated.

  More specifically, the converter power supply device disclosed in Patent Document 1 includes a comparison circuit that determines whether or not the current output from the rectifier is smaller than the reference current, and the voltage across the smoothing capacitor is higher than the reference voltage. It has a comparison circuit that determines whether or not it is large, and a control signal switch that is turned on and off in accordance with the output signals from these two comparison circuits. The control signal switch is a switch for disconnecting the connection between the additional switching circuit and the converter power supply device.

JP 2010-233439 A

  The converter power supply device disclosed in Patent Document 1 detects a current detector that detects a current output from a rectifier and a voltage across a smoothing capacitor to determine whether or not to operate an additional switching circuit. Requires a voltage detector. Furthermore, since the control signal switch for disconnecting the additional switching circuit from the converter power supply device is provided, there are many device configurations, which causes problems such as an increase in the size of the device.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the power converter device and air conditioner which can achieve size reduction of an apparatus.

In order to solve the above problems, the present invention employs the following means.
The present invention is a power conversion device applied to a system including a motor control device for controlling a motor load, which converts AC power into DC power and outputs the DC power to the motor load side, and the converter device A converter control device for controlling the rectifier, the converter device comprising: a rectifier circuit; two DC buses connected to the output side of the rectifier circuit; and a plurality of DC buses connected in parallel to one of the DC buses An inductor, a capacitor provided on the output side of the inductor in the DC bus, one end connected to the DC bus and the other end connected to the other DC bus, the output side of each inductor and the other A wiring for connecting the DC bus, and a plurality of switching elements respectively provided on the plurality of wirings; An input means for acquiring, as input information, a parameter relating to a motor current used in a motor control device for controlling the motor load connected to the output side of the converter device, and operating the switching element based on the acquired input information There is provided a power conversion device comprising first processing means for determining whether or not to perform.

  According to the present invention, parameters relating to the motor current used in the motor control device are input to the converter control device as input information. In the converter control device, whether or not to operate the switching element is determined based on the parameter relating to the motor current acquired from the motor control device. As described above, since it is determined whether to operate the switching element using the information used in the motor control device, it is not necessary to provide a current detector or a voltage detector only for the determination. This makes it possible to simplify the apparatus.

  In the power conversion device, the converter control device acquires, as input information, a requested rotation speed command used in the motor control device and a motor rotation speed command obtained by changing the requested rotation speed command at a predetermined rate. A second processing means may be provided for determining the number of switching elements to be activated based on the requested rotational speed command and the motor rotational speed command.

  Thus, in the converter control device, the number of switching elements to be operated is determined based on the information acquired from the motor control device. Therefore, in order to determine the number of switching elements to be operated, a current detector or a current detector is used. There is no need to provide it, and the device can be simplified.

  In the power converter, the first processing unit includes a comparison unit that compares a parameter related to the motor current or an evaluation value calculated using the parameter with a predetermined reference value set in advance. When the parameter or the evaluation value is equal to or higher than the reference value, it may be determined that the switching element is activated.

  In the power conversion device, the parameter is at least one of motor torque, motor rotation speed, motor current, and motor voltage, and the comparison unit calculates the acquired parameter and a preset reference value. It is good also as comparing.

  In the power conversion device, the parameter may be a motor torque and a motor rotational speed, and the evaluation value may be a value obtained by multiplying the motor torque and the motor rotational speed.

  The present invention relates to the above power conversion device, an inverter device connected to the output side of the power conversion device, which converts DC power from the power conversion device into three-phase AC power and outputs the output, and from the inverter device An air conditioner comprising a compressor motor driven by three-phase AC power and a motor control device for controlling the inverter device is provided.

  There exists an effect that size reduction of an apparatus can be achieved.

It is the figure which showed the peripheral structure of the power converter device applied to the air conditioner which concerns on one Embodiment of this invention, and a power converter device. It is a functional block diagram with which the 1st control apparatus shown in FIG. 1 is provided.

Hereinafter, a power converter and an air conditioner according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a power converter and a peripheral configuration of the power converter in an air conditioner according to an embodiment of the present invention.
As shown in FIG. 1, the power conversion device 1 includes a converter device 2 that converts AC power output from an AC power source 4 into DC power and outputs the converter device, and a converter control device 3 that controls the converter device 2. Yes.

The converter device 2 includes a rectifier circuit 5 that full-wave rectifies AC power. DC buses Lp and Ln are connected to the output side of the rectifier circuit 5.
A plurality of inductors 6a and 6b are connected in parallel to one DC bus Lp. Diodes 7a and 7b are connected in series to the inductors 6a and 6b, respectively. Between the inductor 6a and the diode 7a, the DC bus Ln is connected by a wiring La. Between the inductor 6b and the diode 7b, the DC bus Ln is connected by a wiring Lb. The switching element 8a is connected to the wiring La, and the switching element 8b is connected to the wiring Lb.
The switching elements 8a and 8b are, for example, field effect transistors (FETs).

The inductor 6a, the diode 7a, and the switching element 8a constitute a first switching circuit 10a. Further, the inductor 6b, the diode 7b, and the switching element 8b constitute a second switching circuit 10b (hereinafter, when all switching circuits are indicated, the reference numeral “10” is simply added, and each switching circuit is indicated). ("10a" and "10b" are attached).
In the DC bus, a smoothing capacitor 12 having one end connected to the DC bus Lp and the other end connected to the DC bus Ln is provided on the output side of the switching circuit 10.

Furthermore, an inverter device 15 is connected to the output side of the converter device 2. The inverter device 15 converts the DC power from the converter device 2 into U-phase, V-phase, and W-phase three-phase AC power and outputs it to the motor load 18.
The inverter device 15 includes a switching element corresponding to each phase, and the motor control device 20 controls the switching element, whereby a desired motor current and motor voltage are supplied to the motor load 18. Here, the motor load 18 is a compressor motor.

The motor control device 20 generates, for example, a gate drive signal Spwm of the switching element included in the inverter device 15 based on a requested rotation speed command ω ^* input from a host device (not shown), and outputs the gate drive signal Spwm to the inverter device 15.
Examples of specific methods of motor control include vector control, sensorless vector control, V / F control, overmodulation control, and 1 pulse control.
In order to realize the control as described above, the input DC voltage Vdc of the inverter device 15 and the phase currents iu, iv, iw flowing through the motor load 18 are detected and input to the motor control device 20. ing.

Further, the motor controller 20, in the course of control, the required rotation number command omega ^* motor rotational speed command from .omega.m ^* is determined, the torque (motor current) T for realizing the motor rotational speed command .omega.m ^* The three-phase voltage command is determined based on the calculated torque (motor current) T, and the gate drive signal Spwm is generated from the three-phase voltage command. Since the control of the motor control device 20 is well known, detailed description thereof is omitted here.

Here, the motor rotational speed command ωm ^* is a command for gradually changing the change rate so that the change rate does not exceed a predetermined reference value when the required rotational speed command ω ^* changes. For example, it corresponds to a value after the required rotational speed command ω ^* has passed through the rate limiter.
Information on the required rotational speed command ω ^* , motor rotational speed command ωm ^* , and torque T used in the generation process of the gate drive signal Spwm in the motor control device 20 is output to the converter control device 3.

  The converter control device 3 performs on / off control of the switching element 8a included in the first switching circuit 10a and the switching element 8b included in the second switching circuit 10b. The converter control device 3 is, for example, an MPU (Micro Processing Unit), and has a computer-readable recording medium in which a program for executing each process described below is recorded. The following processing is realized by reading the program recorded in the main memory device such as a RAM and executing it. Examples of the computer-readable recording medium include a magnetic disk, a magneto-optical disk, and a semiconductor memory.

The converter control device 3 includes a first control device 31 and a second control device 32 as main components.
FIG. 2 is a functional block diagram of the first control device 31 provided in the converter control device 3. As shown in FIG. 2, the first control device 31 includes an input unit 41, a first processing unit 42, and a second processing unit 43.

The input unit 41 obtains information on the requested rotational speed command ω ^* , the motor rotational speed command ωm ^* , and the torque T that are output from the motor control device 20 described above, and uses these information as the first processing unit 42 and the second processing unit. Output to 43.

The first processing unit 42 determines whether or not the motor current is larger than a preset reference value. Specifically, the first processing unit 42 compares a parameter relating to the motor current or an evaluation value obtained from these parameters with a preset reference value, and outputs the comparison result as the first signal S1.
Examples of the parameters relating to the motor current include motor torque, motor rotation speed, motor current, and motor voltage.
The first processing unit 42 includes, for example, an evaluation value calculation unit 51 and a comparison unit 52.

The evaluation value calculation unit 51 calculates an evaluation value by multiplying the motor rotational speed command ωm ^* input from the input unit 41 by the motor torque T, and outputs this to the comparison unit 52. The comparison unit 52 compares the input evaluation value with a preset reference value, and outputs an H (high) signal when the evaluation value is equal to or greater than the reference value, and when the evaluation value is less than the reference value. The L (low) signal is output. The H / L signal that is the output of the comparison unit 52 is output to the second control device 32 as the first signal S1.
Here, the H signal means that the switching circuit 10 does not need to be operated, and the L signal means that the switching circuit 10 needs to be operated.

In this embodiment, the evaluation value is compared with the reference value. However, instead of this example, for example, when a constant torque control is performed, the required rotation speed command ω ^* or the motor rotation It may be determined whether or not the motor current is large by comparing the number command ωm ^* with a predetermined reference value set in advance. Further, when the control is performed at a constant rotation speed, the torque T may be compared with a predetermined reference value set in advance. As another example, for example, each phase current iu, iv, iw, input DC voltage Vdc, motor current command value, motor voltage command value, or the like is acquired, and the information is compared with a reference value. It is good.

  When the motor current is large, ripple components generated in the DC buses Lp and Ln of the converter device 2 are large. On the other hand, when the motor current is small, the ripple component generated in the DC buses Lp and Ln is small and falls within a predetermined allowable range. In such a case, it is preferable to stop the operation of the switching circuit 10 and avoid loss due to switching. Therefore, by monitoring the level of the motor current by the first processing unit 42, the switching circuit 10 can be operated only in an effective range, and the switching loss can be reduced. .

The second processing unit 43 determines the number of switching circuits 10 to be operated, and includes a first comparison unit 61, a second comparison unit 62, and an operation number determination unit 63.
The first comparison unit 61 compares the required rotational speed command ω ^* input from the input unit 41 with a preset first reference value, and the required rotational speed command ω ^* is equal to or greater than the first reference value. The H signal is output in the case where the required rotational speed command ω ^* is less than the first reference value.

The second comparison unit 62 compares the motor rotation speed command ωm ^* input from the input unit 41 with a preset second reference value, and the motor rotation speed command ωm ^* is equal to or greater than the second reference value. The H signal is output at the time when the motor rotational speed command ωm ^* is less than the second reference value.
The first reference value and the second reference value may be different values or the same value.

  The operation number determination unit 63 is, for example, an OR circuit (OR circuit), and outputs an H signal when the output of at least one of the first comparison unit 61 and the second comparison unit 62 is an H signal, When the outputs of the first comparison unit 61 and the second comparison unit 62 are both L signals, the L signal is output. The H / L signal that is the output of the operation number determination unit 63 is output to the second control device 32 as the second signal S2. If the second signal S2 is an H signal, it means that there are two switching circuits to be operated, and if it is an L signal, it means that there is one switching circuit to be operated.

As described above, the second processing unit 43 monitors the increase / decrease in the motor current based on the required rotational speed command ω ^* and the motor rotational speed command ωm ^* . When the motor current increases, the ripple component included in the direct current increases, so the two switching circuits 10 are operated to increase the ripple reduction effect. On the other hand, when the motor current decreases, the number of switching circuits 10 to be operated is reduced to reduce the switching loss.

The second control device 32 (see FIG. 1) generates on / off drive signals for the switching elements 8a and 8b based on the first signal S1 and the second signal S2 input from the first control device 31, respectively. This is applied to the switching elements 8a and 8b.
For example, when the second control device 32 receives the L signal as the first signal S1, the second control device 32 determines that it is not necessary to operate both the first switching circuit 10a and the second switching circuit 10b, so A drive signal is not output to the elements 8a and 8b.

  On the other hand, when the H signal is received as the first signal S1, the number of switching elements to be operated is confirmed with reference to the second signal S2. As a result, when the second signal S2 is an H signal, a switching drive signal having a predetermined frequency, for example, a frequency higher than the power supply frequency, is output to both of the switching elements 8a and 8b. As a result, both the switching elements 8a and 8b are on / off controlled at a predetermined frequency, which contributes to power factor improvement and reduction of ripple components.

  Further, when the first signal is an H signal and the second signal is an L signal, either one of the switching elements 8a of the first switching circuit 10a is repeatedly turned on and off at a predetermined frequency. A drive signal is output, and no drive signal is output to the switching element 8b of the second switching circuit 10b. As a result, the second switching circuit 10b stops operating, and only the switching element 8a of the first switching circuit 10a is on / off controlled at a predetermined frequency.

  When the first signal is an H signal and the second signal is an L signal, that is, when one of the switching elements is driven and the other is stopped, the switching element to be driven may be switched. Good. In this way, by switching the switching element to be driven, the operation time of both can be made the same level, and it is possible to avoid the burden of durability on only one side.

Next, operation | movement of the power converter device 1 provided with the said structure is demonstrated with reference to FIG.1 and FIG.2.
First, information such as the input DC voltage Vdc and motor currents iu, iv, and iw is input to the motor control device 20, and the gate drive signal Spwm of the inverter device 15 is generated based on these information. Further, in the motor control device 20, information on the requested rotational speed command ω ^* , the motor rotational speed command ωm ^* , and the torque T used in the process of generating the gate drive signal Spwm is output to the first control device 31 of the converter device 3. Is done.

In the first control device 31, these pieces of information are received by the input unit 41 and output to the first processing unit 42 and the second processing unit 43.
In the first processing unit 42, the evaluation value calculation unit 51 multiplies the required rotational speed command ω ^* and the torque T to calculate the evaluation value, and the comparison unit 52 compares the evaluation value with the reference value. As a result, the H signal is output to the second control device 32 as the first signal S1 if the evaluation value is greater than or equal to the reference value, and the L signal is output as the first signal S1 if the evaluation value is less than the reference value.

In the second processing unit 43, the first comparison unit 61 compares the requested rotational speed command ω ^* input from the input unit 41 with the first reference value. As a result, if the required rotational speed command ω ^* is greater than or equal to the first reference value, the H signal is output to the operating speed determination unit 63, and if the required rotational speed command ω ^* is less than the first reference value, the L signal is output. .

Similarly, the second comparison unit 62 compares the motor rotational speed command ωm ^* input from the input unit 41 with the second reference value. If the motor rotational speed command ωm ^* is greater than or equal to the second reference value, the H signal However, if the motor rotation speed command ωm ^* is less than the second reference value, the L signal is output to the operation number determination unit 63.

  In the operation number determination unit 63, when the output of at least one of the first comparison unit 61 and the second comparison unit 62 is an H signal, the H signal is output to the second control device 32 as the second signal S2, When the outputs of the first comparison unit 61 and the second comparison unit 62 are both L signals, the L signal is output to the second control device 32 as the second signal S2.

  In the second control device 32, when the first signal S1 input from the first control device 31 is the L signal, the operation of the switching circuit 10 is stopped. On the other hand, when the first signal S1 is an H signal, the second signal S2 is confirmed. In this case, if the second signal S2 is an H signal, a drive signal that repeatedly turns on and off at a predetermined frequency is output to the first switching element 8a and the second switching element 8b. On the other hand, if the second signal S2 is an L signal, a drive signal is output to one switching element 8a or 8b, and no drive signal is output to the other switching element 8b or 8a. Thus, only one of the two switching elements 8a and 8b is on / off controlled at a predetermined frequency.

  Thus, according to the power converter device and the air conditioner according to the present embodiment, the control amount used in the motor control device 20 is input to the converter device 3 as input information, and the switching circuit is used using this input information. 10 activation / deactivations are determined and the number of switching circuits to be activated is determined. Thereby, it is not necessary to provide a voltage sensor or a current sensor only to determine whether or not to operate the switching circuit 10 and the number to be operated, and the apparatus configuration can be simplified. As a result, it is possible to reduce the size of the apparatus.

  Further, since the switching circuit 10 is activated / deactivated, and the number of switching elements to be activated is determined based on the motor current, the switching circuit 10 It becomes possible to determine the number of operation to an appropriate number. As a result, the ripple component can be reduced while reducing the switching loss as much as possible.

  In the present embodiment, the case where the two switching circuits 10 are provided is illustrated, but the number of installed switching circuits 10 is not limited. When three or more switching circuits 10 are provided, the reference value in the second processing unit 43 is provided according to the number of installed switching circuits, and the number of switching circuits to be operated and the operation are stopped. The number of switching circuits may be determined dynamically.

  Moreover, although this embodiment demonstrated and assumed the case where the power converter device 1 was applied to the air conditioner, the power converter device which concerns on this invention is widely applicable to the system provided with a motor load.

DESCRIPTION OF SYMBOLS 1 Power converter 2 Converter apparatus 3 Converter control apparatus 4 AC power supply 5 Rectifier circuit 6a, 6b Inductor 7a, 7b Diode 8a, 8b Switching element 10a 1st switching circuit 10b 2nd switching circuit 12 Smoothing capacitor 15 Inverter apparatus 18 Motor load 20 Motor control device 31 First control device 32 Second control device 41 Input unit 42 First processing unit 43 Second processing unit 51 Evaluation value calculation unit 52 Comparison unit 61 First comparison unit 62 Second comparison unit 63 Operation number determination unit

Claims (6)

A power conversion device applied to a system including a motor control device for controlling a motor load,
A converter device that converts alternating current power into direct current power and outputs it to the motor load side;
A converter control device for controlling the converter device,
The converter device is
A rectifier circuit;
Two DC buses connected to the output side of the rectifier circuit;
A plurality of inductors connected to one of the DC buses in parallel;
A capacitor provided on the output side of the inductor in the DC bus, one end connected to one of the DC buses, and the other end connected to the other DC bus;
Wiring connecting the output side of each inductor and the other DC bus;
A plurality of switching elements respectively provided on the plurality of wirings,
The converter control device
Input means for acquiring, as input information, a parameter relating to a motor current used in a motor control device that controls the motor load connected to the output side of the converter device;
A power converter comprising: a first processing unit that determines whether to operate the switching element based on the acquired input information.   The converter control device acquires, as input information, a requested rotational speed command used in the motor control device and a motor rotational speed command obtained by changing the requested rotational speed command at a predetermined rate, and the requested rotational speed command The power converter according to claim 1, further comprising: a second processing unit that determines the number of switching elements to be activated based on the motor rotation speed command. The first processing means includes
Comparing means for comparing the parameter relating to the motor current or an evaluation value calculated using the parameter with a predetermined reference value set in advance,
The power converter according to claim 1 or 2, wherein when the parameter or the evaluation value is equal to or greater than the reference value, the switching element is determined to be activated. The parameter is at least one of motor torque, motor rotation speed, motor current, and motor voltage.
The power converter according to claim 3, wherein the comparison unit compares the acquired parameter with a preset reference value. The parameters are motor torque and motor speed,
The power conversion device according to any one of claims 1 to 3, wherein the evaluation value is a value obtained by multiplying the motor torque and the motor rotation number. The power conversion device according to any one of claims 1 to 5,
An inverter device connected to the output side of the power converter, which converts the DC power from the power converter into three-phase AC power and outputs it;
A compressor motor driven by three-phase AC power from the inverter device;
An air conditioner comprising: a motor control device that controls the inverter device.

Images