JP2011234466A - Motor control device and equipment provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device capable of operating stably without complicating a circuit thereof even under conditions where operating load is high or the amount of load variation is increased; and further to provide an equipment having the motor control device.SOLUTION: A motor control device includes conversion means for converting AC voltage into DC voltage, determination means for determining a switching over between full-wave rectification and voltage doubling rectification, and switching over means for switching over between full-wave rectification and voltage doubling rectification. The motor control device performs a field-weakening control when motor voltage exceeds a predetermined value under full-wave rectification, and switches over to voltage doubling rectification based on a current value of the field-weakening control. In a case where there is a region in which an operation becomes unstable, the motor control device determines voltage doubling rectification switch-over by using a modulation rate.

Description

  The present invention relates to a motor control device and a device including the same.

  2. Description of the Related Art Conventionally, in a refrigerator or a room air conditioner equipped with a motor control device, a configuration is known in which motor-controlled power is supplied by full-wave rectification or double voltage rectification from an AC power supply. Regarding full-wave rectification and voltage doubler rectification, configurations described in Patent Documents 1 and 2 are known.

  Patent Document 1 describes a configuration in which a bidirectional switch that switches between full-wave rectification and voltage doubler rectification is provided, and the energization rate of the bidirectional switch is changed.

  In Patent Document 2, before switching to the voltage doubler rectifier circuit, the DC voltage is boosted to the necessary minimum voltage value, and the DC voltage sudden fluctuation and the peak of the power supply current when switching from the full wave rectifier circuit to the voltage doubler rectifier circuit are disclosed. A configuration for lowering the value is described.

JP 2003-18877 A JP 2004-72958 A

  The configuration described in Patent Document 1 requires a bidirectional switch for changing the energization rate, which complicates the circuit and further increases the cost.

  The configuration described in Patent Document 2 requires a booster circuit, which complicates the circuit and further increases costs.

  Accordingly, in view of the above problems, an object of the present invention is to provide a motor control device capable of stable operation even under conditions of high load conditions and large load fluctuations without complicating the circuit, and a device including the same. It is to be.

  In order to achieve the above object, a motor control device according to the present invention comprises means for converting an AC voltage to a DC voltage, means for determining switching between full-wave rectification and voltage doubler rectification, full-wave rectification and voltage doubler rectification. In the case of full-wave rectification, field-weakening control is performed when the motor voltage exceeds a predetermined value, switching to voltage doubler rectification based on the current value of the field-weakening control, and the operation becomes unstable. In this case, the voltage doubler rectification switching determination is performed using the modulation rate.

  Moreover, the apparatus (refrigerator, air conditioner, and water heater) of this invention has the said motor control apparatus, It is characterized by the above-mentioned.

  According to the present invention, it is possible to provide a motor control device capable of stable operation even under high load conditions or conditions in which load fluctuations are large and a device including the same without complicating the circuit.

The figure which shows the control circuit structure which concerns on the Example of this invention. The figure which shows the relationship between the rotation speed when not performing field-weakening control based on the Example of this invention, and a modulation factor. The figure which shows the relationship between the rotation speed when performing field-weakening control which concerns on the Example of this invention, and a modulation factor. The figure which shows the relationship between the rotation speed when the field weakening control which concerns on the Example of this invention is performed, and a field weakening current. The figure which shows the relationship between the rotation speed when not performing the field-weakening control based on the Example of this invention, and efficiency. The figure which shows the relationship between the rotation speed when performing field-weakening control which concerns on the Example of this invention, and efficiency. The figure which shows the relationship between the rotation speed and efficiency at the time of the stable state which concerns on the Example of this invention, and an unstable state. The flowchart which shows the algorithm in the case of switching to voltage doubler rectification based on the Example of this invention. The flowchart which shows the algorithm in the case of switching to full wave rectification based on the Example of this invention.

  By switching between full-wave rectification and voltage doubler rectification, operation in a wide range of rotation speeds becomes possible. When switching between full-wave rectification and voltage doubler rectification, in order to perform efficient operation, the maximum rotation speed that can be controlled by full-wave rectification is driven by full-wave rectification and the maximum controllable rotation speed is set. When exceeded, switch to voltage doubler rectification. Also, when switching at the number of revolutions, the maximum number of revolutions that can be controlled by full-wave rectification varies depending on the applied voltage and load, so compare the voltage required for motor input with the voltage of the smoothing capacitor (or power supply voltage) When the motor voltage that requires that value (hereinafter referred to as “modulation rate”) exceeds the voltage (or power supply voltage) of the smoothing capacitor, voltage doubler rectification switching is performed. This automatically switches to voltage doubler rectification at the limit of full wave rectification regardless of the applied voltage or load.

  In addition, by performing field-weakening control with full-wave rectification before switching to voltage doubler rectification, the rotation speed at the limit point of full-wave rectification can be made higher and the operation can be performed with high efficiency. it can. However, if field-weakening control is performed, the rotational speed and the modulation rate are not proportional to each other, and the modulation rate cannot be used for switching between full-wave rectification and voltage doubler rectification. Therefore, by using a field weakening current value that increases in proportion to the rotational speed, switching to voltage doubler rectification becomes possible.

  In addition, since the control becomes unstable when turned to the high rotation range by the field weakening control, there is a possibility of abnormal stop under a high load condition such as when the ambient temperature is high or a condition in which the load fluctuation becomes large. Therefore, when full-wave rectification is performed and the required motor voltage exceeds the voltage (or power supply voltage) of the smoothing capacitor, field-weakening control is performed, and field-weakening current is used for voltage doubler rectification switching. Under stable conditions, voltage doubler rectification switching is performed at the modulation rate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a control circuit configuration of the present embodiment. The AC power source 1 is connected to the diode stack 2 and the smoothing capacitor 3 to convert an AC voltage into a DC voltage. That is, a means for converting an AC voltage into a DC voltage is configured. Further, based on the drive signal generated by the drive signal output unit 5 in the microcomputer 4, the three-phase AC signal output unit 6 converts the DC voltage into a three-phase AC signal and outputs it, thereby driving the motor 7. To do.

  The microcomputer 4 includes a stable region determination unit 8, a double voltage rectification switching determination unit 9, and a double voltage rectification switching signal generation unit 10. The stable region determination unit 8 determines whether the region is a stable region or an unstable region. The voltage doubler rectification switching determination unit 9 determines the voltage doubler rectification switching based on the field weakening current value in the stable region and the modulation factor value in the unstable region. Based on the determination result, the voltage doubler rectification switching signal generator 10 outputs a voltage doubler rectification switching signal, and the voltage doubler rectification switching device 11 switches to voltage doubler rectification.

  Next, FIG. 2 is a diagram illustrating the relationship between the rotation speed and the modulation rate when the field weakening control of this embodiment is not performed. In FIG. 2, when there is no field weakening 12, the modulation rate increases in proportion to the increase in the rotational speed. When the motor voltage required for full-wave rectification reaches a modulation rate that exceeds the voltage of the smoothing capacitor 3, switching to voltage doubler rectification is performed and the modulation rate is lowered (see modulation rate switching position 13).

  FIG. 3 is a diagram illustrating the relationship between the rotation speed and the modulation rate when the field weakening control of this embodiment is performed. When the field weakening control is operated, the modulation rate does not increase in proportion to the increase in the rotational speed (see field weakening control position 14). Thereafter, when the field weakening control is stopped by switching to voltage doubler rectification, the modulation rate increases in proportion to the increase in the rotational speed.

  FIG. 4 is a diagram illustrating the relationship between the rotational speed and field weakening current when field weakening control is performed according to the present embodiment. When the field weakening control is activated, the field weakening current increases as the rotational speed increases (see field weakening control position 15). When the field weakening current reaches the set double voltage rectification switching threshold 16, the field weakening is stopped by switching to double voltage rectification. Therefore, the field weakening current becomes zero (see voltage doubler rectification switching position 17).

  FIG. 5 is a diagram illustrating the relationship between the rotational speed and the efficiency when the field weakening control of this embodiment is not performed. The efficiency increases as the rotational speed increases, but the efficiency decreases when switching to voltage doubler rectification (see efficiency switching position 18).

  FIG. 6 is a diagram illustrating the relationship between the rotational speed and efficiency when the field weakening control of this embodiment is performed. In the field weakening control region, although the efficiency is lowered, the transition is made in a state where the efficiency is higher than that in FIG. 5 (see field weakening control position 19). Then, the rotation speed is further increased, and switching to voltage doubler rectification is performed at a rotation speed at which the efficiency is lower than that of voltage doubler rectification (see voltage doubler rectification switching position 20). Thereafter, the efficiency increases as the rotational speed increases.

  FIG. 7 is a diagram illustrating a change in the double voltage rectification switching determination method and a change in efficiency in the stable region and the unstable region of the present embodiment. In the stable region 21, field weakening control is performed. The double voltage rectification switching determination is performed with a field weakening current to perform highly efficient operation.

  In the unstable region 22, field weakening control is not performed. The voltage doubler rectification switching determination is performed based on the modulation rate. Thereby, although the efficiency in the medium speed range is low, it is possible to avoid an abnormal stop such as a step-out.

  FIG. 8 is a flowchart illustrating an algorithm when switching to voltage doubler rectification according to this embodiment. In S101, it is determined whether or not it is a full-wave rectification region, that is, a full-wave rectification region. If it is the full-wave rectification region in S101, the stable region determination is performed in S102. On the other hand, if it is not the full-wave rectification region in S101, the process proceeds to S106 and ends.

  In the stable region determination of S102, it is determined whether or not it is a stable region, and if it is the stable region, the process proceeds to S103 to determine whether the voltage doubler rectification switching current threshold is exceeded. On the other hand, if it is not in the stable region, the process proceeds to S105, and determination is made whether the voltage doubler rectification switching modulation rate threshold value is exceeded.

  In the determination of exceeding the double voltage rectification switching current threshold in S103, it is determined whether the field weakening current exceeds the double voltage rectification switching current threshold. If the threshold value is exceeded, voltage doubler rectification switching is performed in S104, and if not, processing proceeds to S106 and ends.

  In the determination of exceeding the double voltage rectification switching modulation factor threshold in S105, it is determined whether the modulation factor exceeds the double voltage rectification switching modulation factor threshold. If the threshold value is exceeded, voltage doubler rectification switching is performed in S104, and if not, processing proceeds to S106 and ends.

  Next, FIG. 9 is a flowchart illustrating an algorithm when switching to full-wave rectification according to this embodiment. In S201, a voltage doubler rectification region determination is performed. As a result of determining whether or not it is a voltage doubler rectification region, if it is a voltage doubler rectification region, a full wave rectification switching modulation factor threshold value determination is performed in S202. On the other hand, if it is not in the voltage doubler rectification region, the process proceeds to S204 and ends.

  In the determination of exceeding the full-wave rectification switching modulation factor threshold in S202, it is determined whether the modulation factor exceeds the full-wave rectification switching modulation factor threshold. If it exceeds, the process proceeds to S204 and ends. If it does not exceed, full-wave rectification switching is performed in S203, and the process proceeds to S204 and ends.

  As described above, according to the present invention, it is possible to perform switching between full-wave rectification and voltage doubler rectification with an inexpensive relay without providing a booster circuit that increases costs. In addition, by using field-weakening control, the full-wave rectification cannot be controlled, and the double-voltage rectification is inefficiently operated in a rotational speed region with high efficiency, and stable operation is possible even under conditions of high load conditions and large load fluctuations. A motor control device can be obtained.

  In addition, a stable operation can be realized even under conditions where the rotational speed region exceeding the voltage (or power supply voltage) of the smoothing capacitor is operated with high efficiency and the control becomes unstable.

  Moreover, according to the apparatus (Refrigerator, an air conditioner, a water heater, etc.) provided with this motor control apparatus, the stable operation | movement can be obtained also on the conditions where high load conditions and load fluctuations become large.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Diode stack 3 Smoothing capacitor 4 Microcomputer 5 Drive signal output part 6 Three-phase AC signal output part 7 Motor 8 Stable area determination part 9 Double voltage rectification switching determination part 10 Double voltage rectification switching signal generation part 11 Double voltage rectification switching Device 16 double voltage rectification switching threshold (field weakening current)

Claims (4)

Means for converting alternating voltage to direct voltage;
Means for determining switching between full-wave rectification and voltage doubler rectification;
Means for switching between full-wave rectification and voltage doubler rectification,
In the case of full-wave rectification, if the motor voltage exceeds a predetermined value, field weakening control is performed,
Switching to voltage doubler rectification based on the current value of the field weakening control,
A motor control device that performs double voltage rectification switching determination using a modulation factor in a region where the operation becomes unstable.   A refrigerator comprising the motor control device according to claim 1.   An air conditioner comprising the motor control device according to claim 1.   A water heater having the motor control device according to claim 1.

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