JP5881775B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device for improving the power factor of an AC input voltage.

  Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-247101 (Patent Document 1), in a power converter using an AC voltage as an input, a switching element is driven based on an input voltage or an output voltage, The power factor is improved by controlling the flowing current.

JP 2009-247101 A

  However, in the device that controls the current flowing through the reactor by driving the switching element based on the input voltage or the output voltage as described above, the analog value A / D (Analog) from the sensor for measuring the voltage or the sensor output is used. -to-Digital) A delay occurs in the converter, etc., so the value used when processing in the control unit, especially the AC input voltage that is AC, has a different phase from the actual value, and the power factor is sufficiently improved There was a problem that could not be achieved.

  The present invention has been made to solve the above-described problems, and provides a power conversion device that improves a power factor by correcting a delay to a control unit such as a sensor or an A / D converter. It is intended to provide.

The power converter according to the present invention is connected to the input voltage measuring means for measuring the AC input voltage, the input voltage reading means for reading the AC input voltage value measured by the input voltage measuring means, the reactor, and the reactor. Switching element, output voltage measuring means for measuring the output voltage, output voltage reading means for reading the output voltage value measured by the output voltage measuring means, the input voltage read by the input voltage reading means and the output voltage A control unit that controls the on / off state of the switching element based on the output voltage read by the reading unit, a zero cross detection unit that detects a zero cross timing of the AC input voltage, and a zero cross detected by the zero cross detection unit calculating by the control unit based on the input voltage value by the input voltage reading means at the timing And correcting means for correcting the force voltage is those with.

  According to the power converter of the present invention, the delay to the control unit such as the voltage sensor or the A / D converter is calculated from the input voltage value to the control unit at the zero cross timing of the AC input voltage, Since the delay of the input voltage is corrected, the power factor can be improved.

  In addition, since the target current value that flows through the reactor of the power conversion device can be generated based on the zero-cross timing of the AC input voltage, the power factor can be improved by matching the AC input voltage phase with high accuracy.

It is a block diagram of the power converter device which concerns on Embodiment 1 of this invention. It is the figure which showed the relationship between an actual alternating current input voltage and the alternating current input voltage after a sensor value reading means. It is the figure which showed the relationship with actual alternating current input voltage, the alternating current input voltage after a sensor value reading means (at the time of normality), and the alternating current input voltage after a sensor value reading means (at the time of abnormality). It is the figure which showed the relationship of the zero crossing timing of an actual alternating current input voltage and the alternating current input voltage after a sensor value reading means.

  Hereinafter, preferred embodiments of a power converter according to the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
1 is a configuration diagram of a power converter according to Embodiment 1 of the present invention.
In FIG. 1, a power conversion apparatus 100 includes an input voltage sensor 1 as an input voltage measuring unit that measures an AC input voltage, an input current sensor 2 as an input current measuring unit that measures an AC input current, and an output that measures an output voltage. Output voltage sensor 3 as voltage measuring means, first sensor value reading means 4 as input voltage reading means for reading AC input voltage value measured by input voltage sensor 1, AC input current measured by input current sensor 2 A second sensor value reading means 5 as an input current reading means for reading a value; a third sensor value reading means 6 as an output voltage reading means for reading an output voltage value measured by the output voltage sensor 3; , Correction means 8, target current generation means 9, control unit 10, diodes 11, 12, 13, 14 constituting a bridge circuit, react 15, the switching element 16, diode 17, and a capacitor 18. In addition, an AC voltage 19 and a load 20 are connected to the power conversion device 100.

In the power conversion device 100, the input voltage V1 is sensed by the input voltage sensor 1 and read by the first sensor value reading means 4, and the input current I1 is sensed by the input current sensor 2 and the second value is sensed. Based on the input current value read by the sensor value reading means 5 and the output voltage V2 sensed by the output voltage sensor 3 and read by the third sensor value reading means 6, switching is performed by the control unit 10. The ratio of turning on / off the element 16 is calculated and controlled so as to obtain a desired input current and output voltage.

  Here, the first sensor value reading unit 4, the second sensor value reading unit 5, and the third sensor value reading unit 6, for example, convert an analog value from the sensor into a digital value by an A / D converter. The value for conversion is converted into a voltage value and a current value according to a predetermined conversion formula, and a value to be calculated by the control unit 10 is generated. Note that the control unit 10 may execute conversion into a voltage value and a current value according to a predetermined conversion formula.

  Further, the first sensor value reading means 4, the second sensor value reading means 5, the third sensor value reading means 6, and the control unit 10 are normally performed by one MPU (Micro-Processing Unit). There are many.

  In FIG. 1, a bridge circuit composed of diodes 11, 12, 13, and 14 and a one-stone converter circuit composed of a reactor 15, a switching element 16, and a diode 17 are shown as examples, but a semi-bridgeless circuit or an interleave circuit is also illustrated. Well, the converter circuit system is not limited. In FIG. 1, the switching element 16 is a MOS (Metal Oxide Semiconductor), but may be an IGBT (Insulated Gate Bipolar Transistor).

  FIG. 2 is a diagram showing the relationship between the actual AC input voltage and the AC input voltage at the subsequent stage of the first sensor value reading means 4. The AC input voltage 21 is indicated by a solid line, and the first sensor value reading means 4 The subsequent stage AC input voltage 22 is indicated by a broken line. Here, the actual AC input voltage 21 is the input voltage V1 in FIG. As shown in FIG. 2, the AC input voltage 22 at the subsequent stage of the first sensor value reading means 4 is caused by a delay caused by, for example, an A / D converter or the like in the input voltage sensor 1 or the first sensor value reading means 4. A phase delay occurs with respect to the AC input voltage 21.

  Since the AC input voltage is basically a sine wave (sin wave), the phase delay amount is determined from the voltage value of the subsequent stage of the first sensor value reading means 4 at the zero cross timing of the actual AC input voltage 21 shown in FIG. Can be calculated.

  Next, a specific method for calculating the phase delay amount will be described with reference to FIG. The zero cross timing of the actual AC input voltage 21 is detected by the zero cross detector 7. Here, the zero-cross detection unit 7 is represented by a comparator in FIG. 1, but is not particularly limited to this configuration.

  The AC input voltage value V <b> 1 ′ following the first sensor value reading unit 4 is held at the zero cross timing from the zero cross detection unit 7. Here, the AC input voltage value V <b> 1 ′ can be held by a memory in the MPU.

  Further, in order to suppress the influence of disturbance on the AC input voltage value V1 ′ at the subsequent stage of the first sensor value reading means 4 at the zero cross timing, the subsequent stage of the first sensor value reading means 4 at several zero cross timings. A value obtained by averaging the AC input voltage values may be used as the AC input voltage value V1 ′ subsequent to the first sensor value reading means 4 at the zero cross timing.

  As shown in FIG. 3, when the input voltage sensor 1 or the like is abnormal, the output from the first sensor value reading means 4 is greatly delayed to become an AC input voltage (at the time of abnormality) 24 after the sensor reading means. The phase delay amount may be erroneously calculated, but it is corrected whether or not the output from the first sensor value reading means 4 at the zero cross timing is monotonously decreased (monotonically increased at zero cross points different by 180 °). By making a determination by means 8, it is possible to avoid erroneous calculation. If it is determined as abnormal, no correction is made.

  The relationship between the AC input voltage effective value V1rms calculated in advance and the AC input voltage value V1 ′ at the subsequent stage of the first sensor value reading means 4 at the zero cross timing is as follows when the AC input voltage is a sine wave. (1).

  Here, f represents the frequency of the input voltage, and t1 represents the phase delay amount. The phase delay amount t1 is calculated from the equation (1) as the following equation (2).

  Further, as shown in FIG. 4, the phase delay amount t <b> 1 may be calculated from the zero cross timing (zero cross 1) of the first sensor value reading unit 4 from the zero cross timing (zero cross 1) as a starting point.

  Here, in order to suppress the influence of the disturbance on the phase delay amount t1 caused by the zero cross 2 starting from the zero cross 1, the average value of the phase delay amount t1 caused by the zero cross 2 starting from the zero cross 1 at several zero cross timings is obtained. It may be used as the phase delay amount t1.

  The difference ΔV1 (t) between the actual AC input voltage 21 at a certain time t and the AC input voltage 22 in the subsequent stage of the first sensor value reading means 4 is calculated by the following equation (3).

  Therefore, by adding ΔV1 (t) to the input voltage at the subsequent stage of the first sensor value reading means 4, the voltage with respect to the actual AC input voltage 21 due to the delay in the input voltage sensor 1 or the first sensor value reading means 4 The error can be corrected. The calculation of the phase delay amount and the correction of the voltage error are performed by the correction unit 8.

  Here, although not shown in FIG. 1, the delay in the input current sensor 2 and the second sensor reading means 5 is set as a fixed value in advance, and the current error due to the delay is processed by the control unit 10 in the same manner as in the expression (3). You may correct when you do. In this case, the AC input voltage effective value V1rms is replaced with the AC input current effective value I1rms in the equation (3).

  Further, the target current generation means 9 generates a target current value I1 * (t) at a certain time t flowing through the reactor 15 that can be expressed by the following equation (4) with the zero cross timing from the zero cross detection unit 7 as 0 point. Generate.

Here, I1 ^* rms is a target current effective value to be passed through the reactor 15 calculated in advance, and f is the frequency of the input voltage V1.

  As described above, according to the power conversion device 100 according to the first embodiment, the voltage error with respect to the actual AC input voltage 21 due to the delay in the input voltage sensor 1 and the first sensor value reading unit 4 is represented by the zero cross timing of the AC input voltage 21. By correcting based on the voltage value at the subsequent stage of the first sensor value reading means 4 or the phase delay amount by the zero cross timing of the first sensor value reading means 4 starting from the zero cross timing of the AC input voltage 21. The power factor can be sufficiently improved. Further, since the correction is performed based on the delay of the input voltage sensor 1 and the first sensor value reading means 4 for each power conversion device 100, the individual variations of the input voltage sensor 1 and the first sensor value reading means 4 are related. Can also be corrected.

  Here, the voltage value after the first sensor value reading means 4 at the zero cross timing of the AC input voltage 21 or the zero cross timing of the first sensor value reading means 4 starting from the zero cross timing of the AC input voltage 21. By setting the phase delay amount to an average value for several zero cross timings, the influence of disturbance can be suppressed.

  Further, when the delay in the input current sensor 2 and the second sensor value reading means 5 is set as a fixed value in advance and the current error due to the delay is processed by the control unit 10 in the same manner as the equation (3), further force can be obtained by correcting it. The rate can be improved.

  Furthermore, the power factor can be improved by generating a target current value to be passed through the reactor 15 in synchronization with the zero cross timing of the AC input voltage 21.

  DESCRIPTION OF SYMBOLS 1 Input voltage sensor 2 Input current sensor 3 Output voltage sensor 4 1st sensor value reading means 5 2nd sensor value reading means 6 6 3rd sensor value reading means 7 Zero cross detection part 8 Correction means , 9 Target current generating means, 10 control section, 11-14, 17 diode, 15 reactor, 16 switching element, 18 capacitor, 19 AC voltage, 20 load, 21 actual AC input voltage, 22 AC input after sensor reading means Voltage, 23 AC input voltage after sensor reading means (normal time), 24 AC input voltage after sensor reading means (when abnormal) 100 Power converter.

Claims (7)

An input voltage measuring means for measuring an AC input voltage;
Input voltage reading means for reading the AC input voltage value measured by the input voltage measuring means;
Reactor,
A switching element connected to the reactor;
Output voltage measuring means for measuring the output voltage;
Output voltage reading means for reading the output voltage value measured by the output voltage measuring means;
A control unit for controlling the on / off state of the switching element based on the input voltage read by the input voltage reading means and the output voltage read by the output voltage reading means;
Zero-cross detection means for detecting zero-cross timing of the AC input voltage;
Correction means for correcting the input voltage calculated by the control unit based on the input voltage value by the input voltage reading means at the zero-cross timing detected by the zero-cross detection means;
A power conversion device comprising: 2. The electric power according to claim 1, further comprising a correcting unit that corrects an input voltage calculated by the control unit based on an average value of a plurality of times of an input voltage value by the input voltage reading unit at the zero-cross timing. Conversion device. The correction unit corrects an input voltage calculated by the control unit by determining whether the input voltage by the input voltage reading unit at the zero-cross timing is monotonously decreased or monotonically increased. Power converter. An input voltage measuring means for measuring an AC input voltage;
Input voltage reading means for reading the AC input voltage value measured by the input voltage measuring means;
Reactor,
A switching element connected to the reactor;
Output voltage measuring means for measuring the output voltage;
Output voltage reading means for reading the output voltage value measured by the output voltage measuring means;
A control unit that controls the on / off state of the switching element based on the input voltage read by the input voltage reading unit and the output voltage read by the output voltage reading unit;
Zero-cross detection means for detecting zero-cross timing of the AC input voltage;
Correction means for correcting an input voltage calculated by the control unit based on a time from the zero cross timing detected by the zero cross detection means to a subsequent zero cross timing of the input voltage reading means. A power conversion device. And a correction unit that corrects an input voltage calculated by the control unit based on an average value of a plurality of times from the zero-cross timing to a subsequent zero-cross timing of the input voltage reading unit. The power conversion device according to claim 4. An input current measuring means for measuring an AC input current;
Input current reading means for reading the AC input current value measured by the input current measuring means;
With
6. The delay time between the input current measuring means and the input current reading means is previously held as a fixed value, and the input current is corrected based on the fixed value by the control unit. The power converter device as described in any one.   7. The power conversion device according to claim 1, further comprising a target current generation unit configured to generate a target current flowing through the reactor based on a zero-cross timing detected by the zero-cross detection unit. .

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