JP5050485B2 - Electric motor control device and air conditioner equipped with the same - Google Patents

Description

  The present invention relates to an electric motor control apparatus in which a smoothing means including a capacitor and a reactor having a remarkably small capacity is connected to an output terminal of a rectifying means.

Conventionally, a capacitor that constitutes a smoothing means in an electric motor control device that is widely used in home appliances and industrial equipment is a large-capacitance capacitor in order to remove voltage ripple after rectification (for example, non-capacitor). Patent Document 1). For this reason, the jumping voltage due to the regenerative voltage when the motor is stopped is suppressed by the large-capacitance capacitor, and the direct influence on the motor side due to the sudden change of the power supply voltage due to the power supply abnormality is suppressed.
Inverter Drive Handbook Editorial Committee, “Inverter Drive Handbook”, published by Nikkan Kogyo Shimbun, first edition in 1995

  However, in the case of driving by an electric motor control device in which a smoothing means composed of a remarkably small capacitor and a reactor is connected to the output terminal of the rectifying means and the output voltage pulsates at a frequency twice the AC power supply frequency, smoothing is not possible. Since the capacity of the capacitor connected in parallel to the output terminal of the means is small, the voltage jumps due to the regenerative voltage when the motor stops, and if the motor is stopped near the phase where the output pulsation voltage of the smoothing means becomes the maximum value, A voltage exceeding the rating of the component is reached by the jumping voltage.

  Furthermore, when the power supply voltage is suddenly reduced due to an abnormality in the power supply voltage, there is a problem that the motor current jumps and reaches a current exceeding the rating of the component or the motor.

  The present invention solves the above-described problems, and an object of the present invention is to provide an electric motor drive device that suppresses the regenerative voltage and motor current jumping when the electric motor is stopped.

  In order to solve the above-described problems, an electric motor control device according to the present invention includes a rectifying unit that inputs and rectifies an AC voltage, a smoothing unit that smoothes an output voltage of the rectifying unit and outputs the smoothed voltage, and the smoothed voltage is converted into an AC voltage. Orthogonal transformation means for converting to voltage, drive control means for driving and controlling the orthogonal transformation means, voltage detection means for detecting the smoothed voltage, phase detection means for detecting the pulsation phase of the smooth voltage, and the voltage And a stop command output means for outputting a stop command to the orthogonal transform means based on detection values of the detection means and the phase detection means.

  The motor control device according to the present invention can realize motor drive that suppresses the jump of voltage and current when the motor is stopped in the motor control device using the smoothing means formed of a small-capacity smoothing capacitor.

The first invention includes a rectifying means for inputting and rectifying an AC voltage, a smoothing means for smoothing an output voltage of the rectifying means and outputting the smoothed voltage, an orthogonal transform means for converting the smoothed voltage to an AC voltage, Drive control means for driving and controlling the orthogonal transform means, voltage detection means for detecting the smooth voltage, phase detection means for detecting the pulsation phase of the smooth voltage, and detection values of the voltage detection means and the phase detection means And a stop command output means for outputting a stop command for stopping the driving of the electric motor to the orthogonal transform means.

  As a result, the phase and voltage value of the pulsating voltage output from the smoothing means can be detected, and the motor drive can be stopped at a timing at which the jump of the regenerative voltage / motor current can be suppressed.

  According to a second aspect, in the first aspect, the phase detection unit calculates the phase of the pulsation of the smoothing voltage from at least one of a maximum value, a minimum value of a detection voltage value of the voltage detection unit, or a zero cross of an AC power supply. By detecting, the phase of the pulsating voltage output from the smoothing means can be accurately detected, and the motor can be stopped at a timing that suppresses the jump of the regenerative voltage / motor current.

  According to a third invention, in the first or second invention, when the stop command output means outputs a stop command to the orthogonal transform means, the drive control is performed in the vicinity of a pulsation phase at which the smoothing voltage becomes a minimum value. When the means outputs a command to stop the orthogonal transformation means, it is possible to suppress the jumping of the voltage due to the regenerative voltage at the time of the stop.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the stop command output means has a voltage value in the vicinity of a phase where the pulsation of the smoothing voltage becomes a maximum value, beat low Ri by the voltage value of the phase near to be a maximum value, when lower than a reference voltage set by the drive control means outputs a command for stopping the orthogonal transformation means, as instantaneous power failure or power shutdown When the power supply voltage is abnormal, it is possible to suppress the jump of the regenerative voltage / motor current.

  According to a fifth invention, in any one of the first to fourth, the smoothing means includes a capacitor and a reactor, and a resonance frequency of the capacitor and the reactor is 40 times or more of a frequency of the AC power supply. Thus, it is possible to realize high performance of the power supply harmonic characteristics of the input current to the rectifying means.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, by using a film capacitor as the capacitor constituting the smoothing means, the use environment can be selected without worrying about the effect on the life characteristics due to temperature. .

  According to a seventh aspect of the present invention, any one of the first to sixth electric motor control devices is provided in an air conditioner, thereby reducing the size and weight of the device by reducing the capacity of the condenser and reactor constituting the smoothing means, and reducing the size of the apparatus. It is possible to realize driving that suppresses the beat sound generated due to cost reduction and capacity reduction.

  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)
FIG. 1 is a control block diagram of an electric motor control device according to an embodiment of the present invention. The electric motor control device is supplied with power from an AC power source 1 such as a commercial power source that is a single-phase AC power source, and rectifying means 2 configured by a diode bridge for full-wave rectification of the AC voltage supplied from the AC power source 1; Smoothing means 3 that receives the output voltage of the rectifying means 2 and outputs it as a smoothing voltage that pulsates (periodic and rhythmic movement such as a pulse) at a frequency twice that of the AC voltage supplied from the AC power supply 1; Orthogonal transformation means 4 composed of a semiconductor switching element that converts the smoothed voltage output from the smoothing means 3 into a desired AC voltage for driving the electric motor 5, and drive control means 6 for controlling the orthogonal transformation means. The voltage detection means 7 for detecting the smoothed voltage output from the smoothing means 3, and the maximum value and the minimum value of the detection value by the voltage detection means 7 or the zero cross of the AC voltage supplied from the AC power supply 1 (supply AC) Phase detecting means 8 for detecting the phase of the pulsating voltage output from the smoothing means 3 from the time when the pressure becomes 0 V, and the drive control means 6 and the orthogonal transform means 4 based on the detected values of the voltage detecting means 7 and the phase detecting means 8. Stop command output means 9 for outputting a command to stop the operation.

  Here, the smoothing means 3 includes a small-capacity capacitor set so that the resonance frequency is 40 times or more the frequency of the supply voltage of the AC power supply 1, and a reactor for lowering the peak value of the inrush charging / discharging current to the capacitor. have.

  Since the reactor constituting the smoothing means 3 is inserted between the AC power source 1 and the capacitor constituting the smoothing means 3, it may be either before or after the rectifying means 2.

  About the motor control apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, the pulsating voltage waveform output from the smoothing means 3 is shown in FIG. Here, the maximum and minimum values of the pulsating voltage are Vmax and Vmin, respectively, and the timings at that time are t_max and t_min, respectively. Here, the time between adjacent t_max or t_min is defined as a pulsation voltage cycle (in this embodiment, the time between t_min is described as a pulsation voltage cycle, but the time between t_max may be defined as a pulsation voltage cycle. The pulsating voltage cycle may be between the zero crosses of the AC power supply).

  Further, Vth (Vmin <Vth <Vmax) is set so that the pulsation voltage Vdc during the pulsation voltage phase Phase1 <θ <Phase2 is Vdc> Vth.

  Here, when a commercial power supply having a frequency of 50 Hz is used as the AC power supply 1, the values of the reactor and the capacitor constituting the smoothing means 3 are such that the resonance frequency fc = 1 / (2π × √ (L1 × C1)). Is set to be 40 times or more of the frequency of the supply voltage, that is, 2000 Hz or more. Therefore, by using a reactor and a capacitor having a reactance value of 0.5 mH and a capacitance value of 10 μF, fc (= 2250 Hz)> 40 × frequency of the supply voltage of the AC power supply 1 (50 Hz). Thus, by significantly reducing the capacitor capacity of the smoothing means 3, the pulsation (ripple ratio of 80% or more) is increased at twice the frequency of the supply voltage of the AC power supply 1. That is, in this case, the interval between t_min (or between t_max) is 10 msec, and the pulsation voltage pulsates with this 10 sec as one cycle.

  Next, the operation of suppressing the jump of voltage / current when the motor is stopped will be described with reference to FIGS.

  First, in an electric motor control device in which the capacitor capacity constituting the smoothing means 3 is extremely small and the output voltage pulsates greatly, when the electric motor 5 is stopped, the pulsating voltage phase (with the pulsating voltage value exceeding Vth) at the stop timing t0 When Phase 1 <θ <Phase 2) is set, the jump voltage Vmax1 increases due to the regenerative voltage at the time of stop as shown in FIG. 3, and there is a possibility that the rated value of components such as a power device constituting the orthogonal transform means 4 may be exceeded.

  Therefore, when the motor 5 is stopped, a stop command from the drive control device 6 to the orthogonal transformation means 4 is sent to the motor at a pulsation voltage phase (phase θ other than Phase1 <θ <Phase2) at which the pulsation voltage value is lower than the set Vth. By adjusting the timing by the stop command output means 9 so as to output a stop command, the jump voltage Vmax2 (<Vmax1) due to the regenerative voltage can be suppressed as shown in FIG.

Next, a case where an abnormality occurs in the AC power supply 1 will be described. First, when an instantaneous power failure or the like occurs on the AC power supply 1 side, in the motor control device in which the capacity of the capacitor constituting the smoothing means 3 becomes extremely small, the smoothing means as shown in the distortion from the timing t1 shown in FIG. 3 may appear directly, and the influence may be transmitted to the electric motor 5 side to stop.

  In this case, as shown in FIG. 6, when stopping at a voltage value exceeding Vth (timing t0), the jump voltage Vmax1 due to the regenerative voltage becomes large and may exceed the rated value of components such as a power device constituting the orthogonal transform unit 4 There is.

  Therefore, as shown in FIG. 7, when the voltage value between the pulsating voltage phases Phase1 <θ <Phase2 falls below Vth, a stop command output means 9 outputs a command to stop the motor 5, that is, a stop command at Phase1 in FIG. Is output from the stop command output means 9, the jump voltage Vmax2 (<Vmax1) due to the regenerative voltage can be suppressed.

  Next, when the power supply is cut off on the AC power supply 1 side and the power supply is suddenly cut off, the output voltage waveform of the smoothing means 3 is as shown in FIG. When such a voltage is applied to the orthogonal transform means 4, the current flowing through the motor 5 jumps to Imax1 as shown in FIG. 9 until the motor 5 stops, and the power devices constituting the orthogonal transform means 4 The rated value of the electric motor 5 may be exceeded.

  Therefore, as shown in FIG. 10, when the voltage value between the pulsating voltage phases Phase1 <θ <Phase2 falls below Vth, a command to stop the motor 5 is output by the stop command output means 9, that is, the stop command at Phase1 in FIG. Is output from the stop command output means 9, the jump Imax2 (<Imax1) of the current flowing through the electric motor 5 can be suppressed.

  As described above, in the present embodiment, the voltage phase and voltage value of the pulsating voltage output from the smoothing means 3 are detected and the stop timing of the electric motor 5 is controlled, so that the normal power supply and the AC power supply 1 can be stopped. It is possible to suppress the jump of voltage / current during emergency stop due to abnormality.

  As described above, since the motor control device according to the present invention can suppress the jump of voltage / current when the motor is stopped, the rated values of the components to be used can be set to the minimum necessary. Therefore, the present invention can be applied to any motor control device that requires cost reduction and size reduction of the device.

Control block diagram of electric motor control apparatus in embodiment of the present invention Pulsation output voltage waveform diagram of smoothing means in an embodiment of the present invention FIG. 1 shows an example of an output voltage waveform of the smoothing means when stopped in the embodiment of the present invention. FIG. 2 is a diagram illustrating an output voltage waveform example 2 of the smoothing means at the time of stopping in the embodiment of the present invention. FIG. 3 is a diagram illustrating an output voltage waveform example 3 of the smoothing means when stopped in the embodiment of the present invention. FIG. 4 is a diagram illustrating an output voltage waveform example 4 of the smoothing means at the time of stopping in the embodiment of the present invention. FIG. 5 is an output voltage waveform example 5 of the smoothing means when stopped in the embodiment of the present invention. FIG. 6 shows an example of output voltage waveform of the smoothing means when stopped in the embodiment of the present invention. FIG. 1 shows an example of a current waveform of an electric motor when stopped in an embodiment of the present invention. FIG. 2 is a current waveform example 2 of the motor at the time of stopping in the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectification means 3 Smoothing means 4 Orthogonal transformation means 5 Electric motor 6 Drive control means 7 Voltage detection means 8 Phase detection means 9 Stop command output means

Claims (7)

Rectifying means for inputting and rectifying an AC voltage, smoothing means for smoothing the output voltage of the rectifying means and outputting it as a smoothed voltage, orthogonal transform means for converting the smoothed voltage to an AC voltage, and driving control of the orthogonal transform means Drive control means, voltage detection means for detecting the smoothing voltage, phase detection means for detecting the pulsation phase of the smoothing voltage, and the orthogonal transformation means based on detection values of the voltage detection means and the phase detection means. And a stop command output means for outputting a stop command for stopping the driving of the motor. The motor control device according to claim 1, wherein the phase detection unit detects a phase of pulsation of the smoothing voltage from at least one of a maximum value and a minimum value of a detection voltage value of the voltage detection unit or a zero cross of an AC power supply. The stop command output means, when outputting a stop command to the orthogonal transform means, outputs a command for the drive control means to stop the orthogonal transform means in the vicinity of a pulsation phase at which the smoothing voltage becomes a minimum value. 3. The motor control device according to 1 or 2. The stop command output means, the voltage value of the phase near the pulsation is the maximum value of the smoothed voltage is defeated low Ri by the voltage value of the phase near as the maximum value of the pulsation of the last of the smoothed voltage, it is set The motor control device according to any one of claims 1 to 3, wherein the drive control means outputs a command to stop the orthogonal transform means when the voltage becomes lower than the reference voltage . The motor control device according to any one of claims 1 to 4, wherein the smoothing unit includes a capacitor and a reactor, and a resonance frequency of the capacitor and the reactor is 40 times or more a frequency of the AC power supply. . The motor control device according to any one of claims 1 to 5, wherein a film capacitor is used as a capacitor constituting the smoothing means. The air conditioner provided with the electric motor and the electric motor control apparatus of any one of Claims 1-6 which control the said electric motor.

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