JP2008160916A - Blower driver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfy both evasion of circuit damage due to high speed rotation caused by strong wind and driving of a high voltage motor. <P>SOLUTION: A power supply for a blower motor is constituted by inverting a DC power supply or a false DC power supply obtained by rectifying and smoothing an AC power supply into a false AC power supply of arbitrary frequency and voltage using a pulse width modulation means, and a means for detecting the current between the DC power supply and the pulse width modulation means is provided. When the polarity of a detected current coincides with the moving direction of energy from the pulse width modulation means to the DC power supply, the phase of a false AC current generated from the pulse width modulation means is regulated while substantially matching the amplitudes of the false AC current and the DC power supply voltage such that the current level becomes very small or the current flows reversely. Consequently, the terminal voltage of the motor can be lowered, components of low withstand voltage can be used in the DC portion and an efficient motor having a high power generation voltage can be used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to control of a fan driving motor for promoting heat exchange in an outdoor unit of a heat pump air conditioner.

  As a method of improving the efficiency of the heat pump type air conditioner, there is a method of improving the driving efficiency of the blower as an auxiliary machine in addition to the method of improving the efficiency of the compressor as the main power. For these powers, a motor is used in the case of electric drive, but the optimum operating point varies depending on the environmental conditions and load conditions of the heat pump.

  For this reason, the drive motor needs to be efficient over a wide range, but it is difficult to achieve it with an induction motor alone, and by using semiconductor power conversion technology, a pseudo alternating current with variable frequency and variable voltage is generated. A method of efficiently driving a motor over a wide range is employed. In particular, by mounting a permanent magnet on the rotor, power is not required for generating magnetic flux on the rotating side, but the efficiency is excellent.

  FIG. 2 shows a drive circuit configuration for independently driving the compressor motor and the blower motor. The AC power source 1 is rectified by the rectifier diode bridge 4 and smoothed by the smoothing capacitor 6 to constitute a DC power source, and the compressor motor 103 is driven by the DC power source via the three-phase bridge circuit A102. While connecting, it connects so that the air blower motor 3 may be driven via another three-phase bridge circuit B2.

  The driving of each motor is controlled by a control circuit A106 and a control circuit B6. In the drive control of the compressor motor 103, it is difficult to directly detect the rotational position of the motor, and a control method for estimating the rotational position from an applied voltage, current, or the like is employed. On the other hand, in the drive control of the blower motor 3, it is relatively easy to directly detect the rotational position of the motor, the rotational position is detected using the rotational position detector 5, and the detection information is input to the control circuit B6.

  The power sources of the control circuits A and B can be configured from a DC power source created by the smoothing capacitor 7 described above by a technique such as a switching regulator.

  In this configuration, the blower motor 3 shares a driving DC power supply with the compressor motor 103, and the compressor motor 103 has a larger capacity, so the withstand voltage of the components used in the DC power supply circuit is It is reasonable to match the compressor motor as much as possible.

  However, as shown in FIG. 5, the outdoor unit 501 is used outdoors, and the blower may drive the impeller 502 of the blower due to the weather, in addition to the wind generated by itself. In strong winds such as time, the rotational speed may be very high. At this time, if the rotor is a permanent magnet, the generated voltage becomes very high, which may exceed the withstand voltage of the components of the DC power supply circuit described above.

  In particular, a motor with high efficiency has a high voltage to generate, so this problem becomes remarkable. In order to solve this problem, means for shutting off the drive circuit and the motor has been proposed (see, for example, Patent Document 1).

Further, there has been proposed a method for preventing an increase in the terminal voltage of the generator by weakening the wind turbine generator and driving it with field control when the rotational speed becomes high (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 10-4694 JP 2002-233193 A JP 2004-48951 A

  However, the method described in Patent Document 1 has a problem that a part for electrically blocking is required, and the method described in Patent Document 2 requires a complicated calculation based on the dq conversion theory of motor current. It had the problem that. Also, as a method that does not require such means, it is conceivable to keep the voltage generated by the motor very low, but in this case, another problem that the efficiency of the motor is reduced occurs. This is incompatible with the overall goal of building a highly efficient system.

  The present invention solves the above-mentioned conventional problems, and it is possible to reduce the high voltage generated by the blower motor rotated at high speed by strong wind in a simple method, and the efficiency at the time of driving the motor. An object of the present invention is to provide a blower drive device capable of maintaining the above.

  In order to solve the conventional problems, the blower driving device of the present invention detects a direct current, removes a high frequency component as a result of the detection, and the value of the direct current from which the high frequency component has been removed is constant in the regeneration direction. As will be described below, the energization phase to the blower motor is advanced.

  As a result, field weakening driving is performed, and the generated voltage of the motor becomes lower than the DC voltage, the regenerative operation stops, and the voltage rise of the DC part stops. Can be used.

  The blower driving device of the present invention uses a component with a low withstand voltage of the DC portion because the voltage rise of the DC portion does not increase even when the impeller has been rotated at high speed by the wind from the outside. In addition, an efficient motor with a high generated voltage can be used.

  The first invention converts a DC power source or a pseudo DC power source obtained by rectifying and smoothing an AC power source into a pseudo AC current having an arbitrary frequency and an arbitrary voltage using a pulse width modulation means, to a blower motor. A power supply is configured, and means for detecting a current between the DC power supply and the pulse width modulation means is provided, and the polarity of the detected current is such that the energy moves from the pulse width modulation means to the DC power supply. In some cases, the phase of the pseudo alternating current is adjusted while the amplitude of the pseudo alternating current generated from the pulse width modulation means is substantially matched to the voltage of the direct current power source, and the current value is small or in the reverse direction. Control to become current.

  This results in field-weakening drive, the motor's power generation voltage is lower than the DC voltage, the regenerative operation is almost stopped, and the voltage rise in the DC part stops, so the parts with low withstand voltage of the DC part Can be used.

According to a second aspect of the invention, in particular, in the current detection means of the first aspect of the invention, when the average value of the detected current is in the direction in which energy is transferred from the pulse width modulation means to the DC power source, the pulse While the amplitude of the pseudo alternating current generated from the width modulation means is substantially matched to the voltage of the DC power supply, the phase of the pseudo alternating current is adjusted to control the average value of the current to be small or in the reverse direction. When the energy does not move in the direction from the pulse width modulation means to the DC power source, the voltage phase applied to the blower motor is adjusted based on the current for each pulse change of the pulse width modulation means.

  As a result, in addition to the effect of the first invention in which the same current detection means can use a component with a low withstand voltage of the component in the DC portion, there is an effect that highly efficient driving can be realized.

  In particular, the third invention realizes the power supply of the control realizing means of the first invention using a DC power supply or a pseudo DC power supply.

  As a result, even when the DC power source is not operating due to a power failure or the like, the control of the first invention can be performed using the DC voltage due to the rise in the voltage of the blower motor. Parts with low voltage can be used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a circuit configuration diagram of a blower driving device according to a first embodiment of the present invention. In FIG. 1, an AC power source 1 is rectified by a rectifier diode bridge 4 and smoothed by a smoothing capacitor 6 to constitute a DC power source, and a fan motor 3 is driven by this DC power source via a three-phase bridge circuit 2. Connect as you want.

  The drive of the motor is realized by the control circuit 6. In the drive control of the blower motor 3, it is relatively easy to directly detect the rotational position of the motor, the rotational position is detected using the rotational position detector 5, and the detection information is input to the control circuit 6. In the control circuit 6, the voltage across the detection resistor 8, that is, the current between the three-phase bridge circuit 2 and the smoothing capacitor 6 is directly detected for controlling the blower motor 3, and the current is passed through the low-pass filter 9. Enter the average value. As a method for appropriately controlling the motor using the detected current, for example, a method described in Patent Document 3 can be used.

  Next, when the impeller 502 of the blower is rotated at a high speed by a strong wind as shown in FIG. 5, especially when the drive is stopped, the braking force does not work, so it rotates at a high speed. The processing procedure in this case will be described with reference to FIG.

  This process is performed at regular time intervals. When this processing program is activated, it is first determined in decision 901 whether or not it is being driven. If it is being driven, the process program is exited, and if it is not being driven, the process proceeds to decision 902.

  In determination 902, it is checked whether or not the regenerative power is within a predetermined width. If the regenerative power is within the predetermined width, the process proceeds to process 905, and if greater than the predetermined width, the process proceeds to process 903. If NO cannot be detected, the process proceeds to step 906.

  In process 905, the output voltage amplitude is set to the maximum value, that is, the value of the DC voltage, and the series of processes ends. In the process 903, the output voltage amplitude is set to the maximum value, that is, the value of the DC voltage, and an operation of advancing the energization phase is performed in the process 904, and the series of processes is completed. In process 906, a series of processes are ended by turning off the power to the motor.

  FIG. 3 is a graph showing the principle of operation. The average voltage of the resistance is a value indicating in which direction the energy flows, and is “powering” in the forward direction and “regeneration” in the reverse direction. If the regenerative power is large due to strong wind or the like, the voltage of the smoothing capacitor 6 may increase excessively. This becomes more prominent the more efficient the motor with high power generation performance.

  At this time, if the energization phase is changed while the applied voltage to the motor is kept large, the motor terminal voltage can be lowered. This is because when the energization phase is changed, a reactive current flows through the motor, and the terminal voltage can be lowered due to a voltage drop due to the inductance of the motor.

  By reducing the terminal voltage, the regenerative state can be relaxed and an increase in DC voltage can be avoided. Further, in the power running state, no particular action is required because no increase in the DC voltage has occurred.

  The reason why the regenerative state is kept small is that the power of the control circuit can be supplied using regenerative power. That is, by supplying power to the switching power supply 7 with regenerative power, it is possible to realize a control operation even when the AC power supply 1 is in a power failure state.

  It is obvious that the same can be applied to a control system for driving two motors as shown in FIG.

  As described above, the blower drive circuit according to the present invention can provide a method that does not cause circuit damage due to voltage rise only by control even when the fan drive circuit is rotated at a high speed by strong wind or the like. It becomes possible to use a motor.

The circuit block diagram of the air blower drive device in Embodiment 1 of this invention Overall circuit configuration diagram including other motor drives in Embodiment 1 of the present invention and the conventional example The graph which shows the operation principle in Embodiment 1 of this invention The flowchart which shows the control procedure of the control circuit in Embodiment 1 of this invention. Configuration conceptual diagram showing influence of strong wind in Embodiment 1 of the present invention and the conventional example

Explanation of symbols

2 Three-phase bridge circuit 3 Blower motor 6 Smoothing capacitor 7 Switching power supply 8 Detection resistance 9 Low-pass filter

Claims (4)

A DC power supply or a pseudo DC power supply obtained by rectifying and smoothing an AC power supply is converted to a pseudo AC with an arbitrary frequency and voltage using pulse width modulation means, and a power supply for supplying to a blower motor is configured. When the maximum value of the electromotive force generated by the motor exceeds the voltage of the DC power supply,
The phase of the pseudo alternating current is adjusted while keeping the amplitude of the pseudo alternating current generated from the pulse width modulation means substantially equal to the voltage of the direct current power supply so that the terminal voltage of the blower motor does not exceed the voltage of the direct current power supply. The blower drive device characterized by controlling to. A means for detecting a current between the DC power supply and the pulse width modulation means; and when the polarity of the detected current is a direction in which energy is transferred from the pulse width modulation means to the DC power supply, the pulse The phase of the pseudo alternating current is adjusted while the amplitude of the pseudo alternating current generated from the width modulation means is substantially matched with the voltage of the DC power source, and the current value is controlled to be minute or in the reverse direction. The blower driving device according to claim 1. When a means for detecting a current between the DC power supply and the pulse width modulation means is provided, and the average value of the detected currents is a direction in which energy moves from the pulse width modulation means to the DC power supply, The phase of the pseudo alternating current is adjusted while the amplitude of the pseudo alternating current generated from the pulse width modulation means is substantially matched with the voltage of the direct current power source so that the average value of the current becomes a minute or reverse current. Control to
When the energy does not move from the pulse width modulation means to the DC power source, the voltage phase applied to the blower motor is adjusted based on the current for each pulse change of the pulse width modulation means. The blower driving device according to claim 2. The blower drive device according to claim 1, wherein a power source for realizing the control means of the pseudo AC conversion means is realized by using the DC power source or the pseudo DC power source.

Images