JP2009148065A - Motor control unit and air conditioner with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control unit avoiding destruction of an element due to excessive current generated in power restoration of an AC power supply and to provide an air conditioner with the motor control unit. <P>SOLUTION: An instantaneous value detecting means 15 detecting an instantaneous value of the AC power supply 1 is arranged in a capacitor input-type power supply part, and it is connected to an A/D conversion terminal of a microcomputer 13. The microcomputer 13 detects the instantaneous value of the AC power supply at a sufficiently shorter interval than a period of the AC power supply from an output signal of the instantaneous value detecting means 15, and repetitively obtains maximum values of the AC power supply based on the detected latest, previous, and second previous instantaneous values. The obtained maximum value of the AC power supply is repeatedly compared with a determination value which is previously set. When the obtained maximum value of the AC power supply is smaller than the determination value for a predetermined time, it is determined that power interruption or voltage drop occurs, and a stop signal of the power supply part and a motor driving part is output. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric motor control device and an air conditioner equipped with the electric motor control device, and more particularly to a control device for a brushless motor driven by a power supply device that performs power factor improvement by using accumulation and release of energy due to inductance, and the same. The present invention relates to a means for preventing the destruction of the power supply unit at the time of power recovery of the air conditioner equipped with the above and a means for suppressing noise included in the power supply current.

  A power supply device that rectifies alternating current into direct current using a rectifier diode can improve the power factor to some extent by using a reactor that stores and releases energy by inductance. On the other hand, if a reactor is used, Will contain large harmonics (noise), which may adversely affect the power supply system. Therefore, in this type of power supply apparatus, it is particularly necessary to suppress harmonics of the power supply current.

As a harmonic suppression means for a power supply current applied to this type of power supply device, one using a switching element that short-circuits an AC power supply via a reactor is conventionally known. In addition, as an electric motor mounted on an air conditioner, for the purpose of improving efficiency, a brushless motor having a rotor having a permanent magnet and a stator winding composed of a three-phase winding is used. A technique for controlling the driving of the brushless motor by using the power supply device and the harmonic suppression means has been conventionally proposed (see Patent Document 1).
JP-A-3-284168

  The electric motor control device described in Patent Literature 1 creates a conduction ratio of the switching element using an instantaneous value of the power supply current detected by the current detection means so that the power supply current becomes a sine wave. The instantaneous value of the AC power source changes from 0 to the maximum value, and the current passing ratio of the switching element created so that the power source current becomes a sine wave changes between 0 and 1. Usually, the current detection means is provided with a filter unit having a time constant in order to prevent malfunction due to harmonics superimposed on the power supply current, and the current ratio of the switching element is the current detection means. It varies depending on the time constant of the provided filter unit.

  As described above, the instantaneous value of the AC power supply varies from 0 to the maximum value, and the conduction ratio of the switching element created so that the power supply current becomes a sine wave varies between 0 and 1. Therefore, the slope of the instantaneous value of the power supply current when the instantaneous value of the AC power supply changes between 0 and the maximum value is small near the zero cross and large near the maximum value. Therefore, in order to create the conduction ratio of the switching element using the instantaneous value of the power supply current detected by the current detection means so that the power supply current becomes a sine wave, the time of the filter section provided in the current detection means It is desirable to switch the constant appropriately to an optimum value according to the instantaneous value of the power supply current.

  In addition, when AC power is converted from AC power and power is supplied to the load, a current command corresponding to the load power is generated so that the voltage of the smoothing capacitor, which is the output of the power supply unit, becomes a predetermined value. Yes. In this state, when a voltage drop or a power failure occurs in the AC power supply, the current command increases so that the voltage of the smoothing capacitor becomes a predetermined value. When the AC power supply recovers with this current command increased, a large power supply current flows temporarily to the power supply unit due to the time delay when the current command generating means generates the current command, and the switching element can be destroyed. There is sex. In addition, since the voltage of the smoothing capacitor increases at this time, the switching element of the bridge inverter that drives the smoothing capacitor and the non-printing motor may be destroyed. Such inconvenience occurs not only at the time of power recovery after a power failure but also at the time of power recovery after a voltage drop of a predetermined value or more.

  The present invention has been made in order to solve the problems of the prior art. The purpose of the present invention is, firstly, an electric motor control capable of avoiding element destruction due to an excessive current generated when the AC power supply is restored. It is providing the apparatus and the air conditioner carrying this electric motor control apparatus.

  Secondly, an electric motor control device capable of controlling the power supply current to be a sine wave with low noise by appropriately changing the time constant of the filter unit provided in the current detection means, and the electric motor control device are mounted. Is to provide an air conditioner.

  In order to solve the above problems, the present invention firstly relates to an electric motor control device and an air conditioner. First, a rectifier diode that rectifies an AC power source into a DC, a reactor that stores and releases energy by an inductance, and an AC through a reactor. A main circuit having a switching element for short-circuiting a power supply, a reverse blocking diode, and a smoothing capacitor, current detection means for detecting an input current value of the main circuit, a current of the switching element by detecting a load state of the main circuit A current command generating means for generating a command value, and a power supply unit including a current ratio generating means for creating a current ratio of the switching element from the input current value and the current command value, and a rotor having a permanent magnet And a bridge composed of a plurality of motor driving switching elements for driving a brushless motor having a stator winding composed of a three-phase winding. An inverter, a driving means for the switching element for driving the motor, a magnetic pole position detecting means for detecting a rotor magnetic pole position of the non-printer motor, and the bridge inverter based on the rotor magnetic pole position and a speed command inputted from the outside. An electric motor control device comprising an electric motor drive unit equipped with a microcomputer to be controlled, provided with an instantaneous value detecting means for detecting an instantaneous value of the AC power supply, connected to an A / D conversion terminal of the microcomputer, and the microcomputer Detects the instantaneous value of the AC power supply from the output signal of the instantaneous value detection means at an interval sufficiently shorter than the cycle of the AC power supply, and the AC power supply from the detected current instantaneous value, previous instantaneous value, and previous instantaneous value And repeatedly determining the maximum value of the AC power supply and a predetermined determination value. When the maximum value of the obtained AC power supply is smaller than the determination value for a predetermined time, it is determined that a power failure or a voltage drop has occurred, and the power supply unit and the motor drive unit The stop signal is output.

  According to the microcomputer, it is possible to detect the instantaneous value of the AC power source at an interval sufficiently shorter than the cycle of the AC power source output from the instantaneous value detecting means by the timer interruption process, The maximum value within one cycle of the AC power supply can be obtained from the instantaneous value and the change of the instantaneous value before the last time. Further, it is possible to determine whether or not a power failure has occurred by determining a magnitude relationship between the obtained maximum value of the AC power supply and a predetermined determination value. Then, when the maximum value of the obtained AC power supply is smaller than the determination value for a predetermined time, it is determined that a power failure or a voltage drop has occurred, and the power supply unit and the motor drive unit are automatically stopped by a command from the microcomputer. Then, since the power supply unit and the motor drive unit are in a stopped state at the time of power recovery, even if an excessive current occurs due to power recovery, there is no effect on the power supply unit and the motor drive unit, It is possible to prevent the switching elements and the like provided in these parts from being destroyed.

  Secondly, according to the present invention, in the first electric motor control device and the air conditioner, the microcomputer detects and detects an instantaneous value of the AC power source at an interval sufficiently shorter than a cycle of the AC power source. The zero crossing and maximum value of the AC power source are repeatedly obtained from the instantaneous value, the previous instantaneous value, and the previous instantaneous value, and one or more determination values are set between the obtained zero cross and the maximum value, and the detected value is detected. Determine the magnitude relationship between the instantaneous value of the AC power supply and the judgment value, and based on the judgment result, the power factor of the power supply current can be improved regardless of the magnitude relation between the instantaneous value of the AC power supply and the judgment value. In order to reduce noise, the time constant of the filter unit provided in the current detection unit is changed.

  As described above, according to the microcomputer, the maximum value within one cycle of the AC power supply can be obtained by the timer interrupt process, and the zero cross within one cycle can be detected by the same process. In the vicinity of the zero cross of the instantaneous value of the AC power supply, the voltage is small, but the rate of change over time is large.Therefore, in order to improve the power factor of the power supply unit, it is necessary to reduce the time constant of the filter unit. Even if the time constant is reduced, the voltage to be handled and the current to be switched are small, and the generated noise is also small, so that malfunction caused by noise does not become a problem. On the other hand, in the vicinity of the maximum value of the instantaneous value of the AC power supply, the voltage is large, but the temporal change rate is small, so it is necessary to increase the time constant of the filter unit in order to prevent malfunction caused by noise. Even if the time constant of the filter unit is increased, the power factor does not decrease because the voltage to be handled and the current to be switched are large. Therefore, by determining the magnitude relationship between the detected instantaneous value of the AC power supply and a preset determination value, and appropriately changing the time constant of the filter unit provided in the current detection means based on the determination result, The influence of noise due to switching can be reduced without causing a reduction in power factor.

  According to the present invention, when a power failure or voltage drop occurs in the AC power supply, the power supply unit and the motor drive unit can be automatically stopped by detecting the power failure or voltage drop. Can be destroyed.

  Further, according to the present invention, the magnitude relationship between the detected instantaneous value of the AC power supply and a preset determination value is determined, and the time constant of the filter unit provided in the current detection means is appropriately set based on the determination result. Since the change is made, it is possible to improve both the power factor and reduce the influence of noise due to switching.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of an electric motor control device according to the present invention and an air conditioner equipped with the same will be described with reference to FIGS. 1 to 6. 1 is a configuration diagram of an electric motor control device according to the embodiment, FIG. 2 is an operation explanatory diagram of a power supply unit according to the embodiment, FIG. 3 is an operation explanatory diagram of an electric motor driving unit according to the embodiment, and FIG. 4 is according to the embodiment. FIG. 5 is an operation explanatory diagram of power failure detection according to the embodiment, and FIG. 6 is an operation explanatory diagram of constant switching according to the embodiment.

  In FIG. 1, 1 is an AC power source, 2 is a rectifier diode, 3 is a reactor, 4 is a switching element, 5 is a reverse blocking diode, 6 is a smoothing capacitor, 7 is an input current detecting means, 8 is a current command generating means, 9 Is a conduction ratio generating means, and constitutes a power supply unit. Further, 10 is a switching element that constitutes a bridge inverter and drives the non-printing motor, 11 is a driving means for the switching element of the bridge inverter, 12 is a magnetic pole position detecting means, and 13 is a microcomputer. It is composed. Further, 14 is a brushless motor, and 15 is a means for detecting an instantaneous value of the AC power supply.

  The so-called capacitor input type power supply unit shown in FIG. 1 has a current only in the vicinity of the maximum value where the power supply voltage is higher than the voltage of the smoothing capacitor 6 as shown in FIG. Flows. On the other hand, the flow ratio generating means 9 allows the switching element 4 to pass through based on the input current information obtained by the current detecting means 7 and the current command generated from the current command generating hand pitch 8 according to the load state. When a flow ratio is created and the switching element 4 is turned on and off with a signal corresponding to the current ratio created by the current flow ratio generation means 9, as shown in FIG. Flows sinusoidally. Various control methods for making the input current sinusoidal have been devised, but in the example described in Patent Document 1, current command generation for generating a current command according to the input current information obtained by the current detection means 7 and the load state The on / off of the switching element 4 is controlled by the product of the current command of the means 8.

  Next, the operation of the electric motor drive unit will be described. FIG. 3 illustrates the position detection operation by the so-called sensorless 120 ° energization method for detecting the rotor position from the back electromotive force included in the terminal voltage of the stator winding of the non-printer motor 14. In this method, the magnetic pole position of the rotor is detected by using the back electromotive force of the non-energized winding by the action of the position detecting means 12.

  The time corresponding to the commutation delay angle from the reference position to the energized phase switching of the armature winding set in advance from the reference position is the reference position where the counter electromotive force and neutral point potential of the non-energized winding are crossed After the elapse of time, a position detection signal for switching the energized phase of the armature winding is generated. Here, the commutation delay angle from the reference position to the preset switching of the energized phase of the armature winding is 30 ° in electrical angle when the rotor position is operating correctly, as shown in FIG. is there. The position detection means 12 creates a position detection signal from each of the three phases and outputs it to the microcomputer 13. The microcomputer 13 performs commutation processing based on the position detection signal and performs speed control so that the rotational speed of the non-printer motor 14 matches the speed command. The driving means 11 amplifies the output of the microcomputer 13 and drives the switching element of the bridge inverter. The switching element 10 constitutes a bridge inverter and switches the current supplied to the non-printing motor to drive it.

  In the motor control device that combines the power supply unit and the motor drive unit that perform the above operations, an instantaneous value detection unit 15 that detects an instantaneous value of the AC power supply 1 is provided. This instantaneous value detection means 15 detects the voltage of the output of the rectifier diode 2, and the detected waveform is the full-wave rectified waveform shown in FIG. The microcomputer 13 detects the instantaneous value of the AC power supply 1 at intervals sufficiently shorter than the cycle of the AC power supply 1 by timer interrupt processing. In the example of FIG. 4, an example in which the instantaneous value of the AC power source 1 is detected at times tl, t2,..., T7, t8 is illustrated, and the instantaneous value of each AC power source 1 is represented by vl, V2,. .., V7, V8. The microcomputer 13 sets the instantaneous value of the AC power source 1 at the time of the most recent timer interrupt to the current instantaneous value, the instantaneous value of the AC power source 1 at the previous timer interrupt to the previous instantaneous value, and the instantaneous value of the AC power source 1 at the previous timer interrupt. The value is stored in a storage unit (not shown) as an instantaneous value the previous time. By comparing the instantaneous values of these three generations of the AC power supply 1, approximate positions of the zero crossing and the maximum value can be obtained. That is, in the example of FIG. 4, the vicinity of time t3 is a zero cross, and V4 is the instantaneous value, V3 is the previous instantaneous value, and V2 is the instantaneous value of the previous time, and V2> V3 and V3 <V4.

  If the previous instantaneous value is smaller than the previous instantaneous value and the current instantaneous value, the time of the previous timer interruption becomes zero cross. Similarly, if the previous instantaneous value is larger than the previous instantaneous value and the current instantaneous value, the previous timer interrupt time becomes the maximum value.

  By obtaining the maximum value of the AC power source 1 in this way, the instantaneous value of the AC power source 1 is constantly monitored as shown in FIG. 5, and a power failure occurs when the maximum value is smaller than a predetermined determination value for a predetermined time. It can be determined that it has occurred. When a power failure occurs, the malfunction and destruction of the motor control device can be prevented by stopping the operation before an abnormality occurs in the power supply unit and the motor drive unit. FIG. 5 shows an example of a voltage drop, but the same applies to a power failure.

  As described above, the electric motor control device according to the present embodiment can obtain the zero crossing and maximum time of the AC power supply 1 by the timer interrupt process, and this can be used within one cycle of the AC power supply 1. It is also possible to switch the time constant of the filter unit provided in the current detection means 7.

  That is, it is preferable that the time constant of the filter unit is large in order to suppress noise accompanying the switching operation of the switching element 4. However, if the time constant is increased, a failure occurs in improving the power factor, which is the original purpose of the power supply unit. This is because the instantaneous value of the power supply current detected by the current detection means becomes a delayed phase due to the time constant of the filter unit, and the power supply current deviates from the sine wave.

  In the vicinity of the zero cross of the instantaneous value of the AC power supply 1, since the voltage is small but the temporal change rate is large, it is necessary to reduce the time constant of the filter unit in order to obtain an accurate sinusoidal power supply current. On the other hand, the voltage near the maximum value of the instantaneous value of the AC power supply 1 is large, but its temporal change rate is small. Therefore, even if the time constant of the filter unit is increased, an accurate power supply current having a sine waveform can be obtained. . In the vicinity of the zero cross of the instantaneous value of the AC power supply 1, the voltage is small and the switching current is small. Therefore, even if the time constant of the filter unit is reduced, the generated noise is small and the power factor can be improved. it can. On the other hand, in the vicinity of the maximum instantaneous value of the AC power supply 1, the voltage is large and the switching current is large. Therefore, the noise can be reduced by increasing the time constant of the filter unit.

  Therefore, in this embodiment, as shown in FIG. 6, a determination value is set between the zero cross and the maximum value, and the magnitude relationship between the detected instantaneous value of the AC power supply 1 and the determination value is determined, When the detected instantaneous value of the AC power supply 1 is smaller than the determination value, the microcomputer 13 reduces the time constant of the filter unit provided in the current detection means 7, and the detected instantaneous value of the AC power supply 1 is obtained. When it is larger than the determination value, the microcomputer 13 increases the time constant of the filter section provided in the current detection means 7. Thereby, the influence of the noise by switching can be aimed at, without causing the fall of a power factor.

  In the example of FIG. 6, only one determination value is set and the number of time constant switching stages of the filter unit is two. However, the gist of the present invention is not limited to this, and two or more determinations are made. By setting a value, the number of stages for switching the time constant of the filter unit can be set to three or more stages.

  In the above embodiment, the position detection method of the brushless motor 14 has been described by taking a so-called sensorless 120 ° energization method as an example, but the gist of the present invention is not limited to this, and other positions Even when the detection method and other energization methods are employed, the same effects as those of the embodiment can be obtained.

It is a lineblock diagram of the electric motor control device concerning an embodiment. It is operation | movement explanatory drawing of the power supply part which concerns on embodiment. It is operation | movement explanatory drawing of the electric motor drive part which concerns on embodiment. It is operation | movement explanatory drawing of the timer interruption process which concerns on embodiment. It is operation | movement explanatory drawing of the power failure detection which concerns on embodiment. It is operation | movement explanatory drawing of the constant switching which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power source 2 Rectifier diode 3 Reactor 4 Switching element 5 Reverse blocking diode 6 Smoothing capacitor 7 Current detection means 8 Current command generation means 9 Current ratio generation means 10 Switching element for driving a brushless motor 11 Switching element drive means 12 Magnetic pole position detection Means 13 Microcomputer 14 Brushless motor 15 Instantaneous value detection means of AC power supply

Claims (4)

A main circuit including a rectifier diode that rectifies an AC power source into DC, a reactor that stores and releases energy by inductance, a switching element that short-circuits the AC power source through the reactor, a reverse blocking diode, and a smoothing capacitor, and the main circuit Current detection means for detecting an input current value of the main circuit, current command generation means for detecting a load state of the main circuit and generating a current command value of the switching element, and the switching from the input current value and the current command value A plurality of electric motor drives for driving a brushless motor having a power source unit having current ratio generating means for creating a current ratio of elements, a rotor having a permanent magnet, and a stator winding composed of three-phase windings Bridge inverter comprising switching elements for driving, driving means for switching elements for driving the motor, rotor of the non-printing motor In motor control device comprising a motor drive unit provided with the microcomputer for controlling said bridge inverter based on the speed command input pole magnetic pole position detection means for detecting a position, and from the rotor magnetic pole position and the outside,
Instantaneous value detection means for detecting the instantaneous value of the AC power supply is provided and connected to the A / D conversion terminal of the microcomputer, and the microcomputer determines the output signal of the instantaneous value detection means from the period of the AC power supply. The instantaneous value of the AC power source is detected at sufficiently short intervals, and the maximum value of the AC power source is repeatedly determined from the detected current instantaneous value, the previous instantaneous value, and the instantaneous value of the previous time, and the maximum value of the obtained AC power source is determined. And repeatedly determining the magnitude relationship between the predetermined determination value and the maximum value of the obtained AC power source is smaller than the determination value for a predetermined time, it is determined that a power failure or voltage drop has occurred, A motor control device that outputs a stop signal for the power supply unit and the motor driving unit.   The microcomputer detects the instantaneous value of the AC power supply at an interval sufficiently shorter than the cycle of the AC power supply, and calculates the zero crossing and the maximum value of the AC power supply from the detected current instantaneous value, previous instantaneous value and previous instantaneous value. While repeatedly obtained, a determination value of 1 or more is set between the obtained zero cross and the maximum value to determine the magnitude relationship between the detected instantaneous value of the AC power supply and the determination value, and the determination result Based on the time constant of the filter unit provided in the current detection means so that the power factor of the power supply current can be improved and noise is reduced regardless of the magnitude relationship between the instantaneous value of the AC power supply and the determination value. The motor control device according to claim 1, wherein the motor control device is changed. A main circuit including a rectifier diode that rectifies an AC power source into DC, a reactor that stores and releases energy by inductance, a switching element that short-circuits the AC power source through the reactor, a reverse blocking diode, and a smoothing capacitor, and the main circuit Current detection means for detecting an input current value of the main circuit, current command generation means for detecting a load state of the main circuit and generating a current command value of the switching element, and the switching from the input current value and the current command value A plurality of electric motor drives for driving a brushless motor having a power source unit having current ratio generating means for creating a current ratio of elements, a rotor having a permanent magnet, and a stator winding composed of three-phase windings Bridge inverter comprising switching elements for driving, driving means for switching elements for driving the motor, rotor of the non-printing motor There is provided an electric motor control device comprising a magnetic pole position detecting means for detecting a pole position, and an electric motor drive unit having a microcomputer for controlling the bridge inverter based on the rotor magnetic pole position and a speed command inputted from outside. In air conditioner,
Instantaneous value detection means for detecting the instantaneous value of the AC power supply is provided and connected to the A / D conversion terminal of the microcomputer, and the microcomputer determines the output signal of the instantaneous value detection means from the period of the AC power supply. The instantaneous value of the AC power source is detected at sufficiently short intervals, and the maximum value of the AC power source is repeatedly determined from the detected current instantaneous value, the previous instantaneous value, and the instantaneous value of the previous time, and the maximum value of the obtained AC power source is determined. And repeatedly determining the magnitude relationship between the predetermined determination value and the maximum value of the obtained AC power source is smaller than the determination value for a predetermined time, it is determined that a power failure or voltage drop has occurred, An air conditioner that outputs a stop signal of the power supply unit and the electric motor drive unit.   The microcomputer detects the instantaneous value of the AC power supply at an interval sufficiently shorter than the cycle of the AC power supply, and calculates the zero crossing and the maximum value of the AC power supply from the detected current instantaneous value, previous instantaneous value and previous instantaneous value. While repeatedly obtained, a determination value of 1 or more is set between the obtained zero cross and the maximum value to determine the magnitude relationship between the detected instantaneous value of the AC power supply and the determination value, and the determination result Based on the time constant of the filter unit provided in the current detection means so that the power factor of the power supply current can be improved and noise is reduced regardless of the magnitude relationship between the instantaneous value of the AC power supply and the determination value. The air conditioner according to claim 3, wherein the air conditioner is changed.

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