JP4976769B2 - Sine wave effective value detection device and sine wave power supply device using the same - Google Patents

Description

  The present invention relates to a sine wave effective value detection device that quickly detects an effective value of a sine wave, and a sine wave power supply device that stably outputs an effective value of a desired sine wave using the same. In particular, the sine wave power supply device relates to a technology that can immediately respond to load fluctuations and maintain a constant output effective value.

  Generally, in a sine wave power supply device, load fluctuation occurs when the load is turned on / off or a specific function of the load device is switched. However, as a sine wave power supply device, the load fluctuation is quickly absorbed. Therefore, it is desired that the output be constant. At that time, a method of detecting the output of the sine wave power supply device and controlling it constant is employed.

  In many cases, the output of the sine wave power supply device is generally defined by an effective value (RMS) (see Patent Document 1). By the way, as a technique for detecting the effective value of the output of the sine wave, a technique using an element (for example, a thermocouple) that performs electric-thermal-RMS conversion, or an IC (for example, model name: AD736) is commercially available. There is a technique for performing RMS conversion by analog processing. The technique using heat has a drawback that the response by heat is slow. Also, for example, in the RMS conversion by analog processing of the AD 736 of the IC, according to the experiment, the time from when the AC 100V is turned on and the input is cut off until the output signal actually decreases has a delay of about 100 ms. .

  As a technique for detecting an effective value, there is a method of A / D converting a sine wave and obtaining an effective value by digital calculation using a multiplier or DSP processing. This is an operation in which an instantaneous value of a sine wave is acquired by an A / D converter using a predetermined clock (for example, Patent Document 1 uses 256 / cycle and its half cycle is 128), and each acquired data is squared. This is a method of repeating the process of obtaining the sum and performing this for one cycle of the sine wave, and then performing the square root calculation to obtain the effective value. In this case, since the number of data used for the arithmetic processing is large, the processing takes time, and the response of the effective value of the output to the instantaneous value of the input tends to be delayed as in the analog processing. In order to speed these up, if a high-speed CPU, high-speed program processing, and a high-speed A / D converter are employed as in Patent Document 1, there is a possibility that faster processing may be obtained, but the configuration scale becomes large, It becomes an expensive device.

JP 2002-204577 A

  An object of the present invention is to provide a sine wave effective value detection device that can detect an effective value by reducing response delay by a simple calculation using an inexpensive CPU, and a sine wave power source that responds quickly to load fluctuations using the sine wave effective value detection device Is to provide a device.

  In order to solve the above-mentioned problems, the present invention calculates an effective value of a sine wave, and in order to detect whether the sine wave is the calculated effective value or not, the calculation is not necessarily performed over the entire cycle. Whether the effective value of the input sine wave is large, small, or small by detecting the instantaneous value at the timing when the instantaneous value of the input sine wave is essentially the effective value. Is focused on being able to judge. Then, if only large and small comparisons are made, it is possible to use one point, and if this is used in a sine wave power supply device, it was noted that load fluctuation can be suppressed very quickly.

According to the first aspect of the present invention, there are provided a plurality of timing signals in which the absolute value of the amplitude of a sine wave signal having a predetermined cycle as a detection target becomes the same value as the effective value of the sine wave signal within one cycle, and timing signal generating means for generating a timing signal as a timing signal and the minimum value becomes the maximum value in one period of a sine wave at each timing signal output from said timing signal generating means, received sinusoidal signal sampling means for sampling, calculates the average value of the absolute value of the amplitude obtained by sampling based on the plurality of timing signals, sampled on the basis of the two timing signals to be the maximum and minimum values the mean value is corrected according to the difference between twice the amplitude value of the sine wave to the difference between the target value between was collected using the received corrected mean value And a calculating means for outputting as an effective value of the sine wave signal, with.

According to the second aspect of the present invention, the variable means for variably outputting the voltage of the sine wave and the absolute value of the amplitude of the desired sine wave signal become the same value within one cycle as the effective value of the sine wave signal. a plurality of timing signals, said desired timing signal generating means for generating a timing signal as a timing signal and the minimum value becomes the maximum value in one period of the sine wave, each timing output from the timing signal generating means A sampling means for sampling the voltage output from the variable means with a signal, and calculating an average value of absolute values of amplitude obtained by sampling based on the plurality of timing signals, and the maximum value and the minimum value, The average value is compensated according to the difference between the difference between the values obtained by sampling based on the two timing signals and the twice the amplitude value of the target sine wave. And an arithmetic means for outputting the corrected mean value, effective value which the calculation means outputs has a control unit for varying relative to said varying means so that the effective value of the desired sine wave .

The invention according to claim 3, a switching means for converting the alternating current by switching a pulse of a predetermined period upon receiving the DC voltage, a filter for converting a sine wave and smoothing the output of said switching means, the desired a plurality of timing signals absolute value of the amplitude of the sine wave is the same value by the effective value and one cycle of the sinusoidal signal, a timing signal and a minimum value as a maximum value in one period of the desired sine wave and timing signal generating means for generating a timing signal consisting, at each timing signal output from said timing signal generating means, sampling means for sampling the voltage the filter output samples based on the plurality of timing signals It calculates the average value of the absolute values of the obtained amplitude Te, two timing to be the maximum and minimum values The average value is corrected according to the difference between the values obtained by sampling based on the signal and twice the amplitude value of the target sine wave, and the corrected average value is received by the received sine calculating means for outputting as an effective value of the wave signal, by changing the width of the pulses on the basis of the effective value of said calculating means outputs, as the output voltage of said filter, the effective value of the desired sine wave And a control unit for controlling.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the plurality of timings are four timings, and the control unit includes the four timing signals and the maximum in one cycle immediately before the control. After receiving the effective value calculated based on the value sampled by the two timing signals that are the value and the minimum value from the calculation means, the output voltage of the filter becomes the effective value of the desired sine wave It was set as the structure controlled in this way.

According to the first to third aspects of the present invention, a plurality of timings (the absolute value of the instantaneous value of the sine wave signal) in which the amplitude of the sine wave signal of a predetermined period becomes the same value as the effective value of the sine wave signal within one period. In this case, the timing is four times in one cycle.), The amplitude value of the received sine wave signal is detected, and the effective value is obtained from the average value of the detected plurality of amplitude values. With a relatively low-cost and low-speed CPU, the response delay can be reduced and detected. Further, when the sine wave is distorted, the maximum value and the minimum value of the sine wave are detected, and based on this, the sine wave distortion can be reduced and measured.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a functional configuration and timing of a sine wave effective value detection device according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a functional configuration of the sine wave power supply device according to the second embodiment. FIG. 3 is a diagram for explaining the switching operation in FIG. 4 and 5 are diagrams for explaining an example of control of the output voltage according to the second embodiment. FIG. 6 is a diagram illustrating an example of effective value detection of the sine wave effective value detection device.

[First Embodiment]
In FIG. 1, a timing signal generator 1 outputs a pulse signal indicating an effective value of a desired sine wave signal to be detected in advance and a timing at which the desired sine wave signal intersects. For example, as shown in FIG. 1B, a pulse (sequence) indicating the timing at which the instantaneous value of a known sine wave as a detection target intersects the known effective value of the sine wave, that is, the timing at which both become the same value. ) Is generated (t1, t3, t4, and t6 in FIG. 1B correspond to the timing). Further, a timing signal indicating the timing at which the instantaneous value of the known sine wave as the detection target becomes the maximum value and a timing signal at which the instantaneous value becomes the minimum value are generated (t2 and t5 in FIG. 1B correspond to the timing. ). If the sine wave is a sine wave without distortion, each timing with respect to the period T of the sine wave is the same regardless of the magnitude of the amplitude. That is, if the sine wave is expressed by Asin 2πt / T (A is amplitude), the effective value is A / 2 ^1/2 , and the timings t1, t3, t4, and t6 are absolute values of sin2πt / T = 1. The timing t satisfies / ^1/2 , and the timings t2 and t5 are timings t at which the absolute value of sin2πt / T = 1.

  As described above, since the timings t1 to t6 are all calculated from each information, the timing signal generating means 1 generates each timing signal by generating a pulse at the timing determined by the calculation. . For example, if the time axis of one cycle is handled as digital data (expressed as index 64) divided into 64, t1, t3, t4, and t6 are indicated by 8, 24, 40, and 56, respectively. , T2, and t5 are represented by indexes 16 and 48, respectively. Therefore, the timing signal can be generated by dividing one cycle T into 64 and generating a pulse at each index.

  The sampling unit 2 includes an ADC (A / D converter), receives an input sine wave signal (a sine wave indicated by a broken line in FIG. 2B), and receives a timing signal (from the timing signal generation unit 1). Sampling is performed at t1 to t6) and converted to digital data. The input sine wave signal is sampled by the sampling means 2 after being shifted by the voltage Vs for convenience of ADC and the like. The amplitude values sampled at timings t1, t3, t4, and t6 are output as L1, L2, L3, and L4, and the amplitude values sampled at timings t2 and t5 are output as Lm and Ls.

The calculation means 3 performs the calculation of the following expression 1 based on the sampled amplitude value.
(Expression 1): Average effective value of input sine wave signal = {(L1−Vs) + (L2−Vs) + (Vs−L3) + (Vs−L4)} / 4
= (L1 + L2-L3-L4) / 4
Here, (L1-Vs), (L2-Vs), (Vs-L3), and (Vs-L4) indicate the absolute values of the amplitudes sampled from the input sine wave. The expression (1) shows the average value obtained by sampling at four points, which is, for example, the average of two points depending on the noise contained in the input sine wave and the measurement accuracy to be obtained. Depending on the application, it may be one point (no average). Moreover, the average for two periods, the average for three periods, or a cumulative average may be used. However, it is preferable to use properly depending on the application because time is required.

Furthermore, the calculation means 3 performs the calculation of the following formula 2 to correct the average value.
(Expression 2) Corrected average value = (L1 + L2-L3-L4) / 4
+ K (Lm-Vs-Vp)
+ K (Vs-Ls-Vp)
= (L1 + L2-L3-L4) / 4
+ K (Lm-Ls-2Vp)
Note that k (Lm−Vs−Vp) is a correction term based on the difference between the maximum value of the input sine wave signal and the maximum value (amplitude value Vp) of the original sine wave, and k (Vs−Ls− Vp) is a correction term based on the difference between the minimum value of the input sine wave signal and the minimum value of the original sine wave (the amplitude value is Vp). For k, if the distortion of the input sine wave is constant, it is preferable to adopt an empirically determined value accordingly. Generally, k = 1/2 to 1/4.

  When there is no distortion in the input sine wave signal, the effective value can be detected by the calculation according to Equation 1. When the input sine wave signal is distorted, it is possible to detect the effective value by reducing the influence of the distortion by roughly correcting the influence of the distortion by the calculation according to Equation 2.

  The arithmetic means 3 can be constituted by a low-cost CPU and software, or may be assembled by logic using a gate array or the like. At this time, if the calculation is performed in binary, a 1/2 calculation can be achieved by shifting the digit of the value to the right by one digit. Since the above-mentioned ¼ calculation only needs to be shifted to the right by two digits, the calculation is easy and fast.

  In FIG. 1B, only one cycle of timing is shown. However, when this is repeatedly detected in subsequent cycles, the effective value is obtained by calculating the average value of the cycle once per cycle. The method and each repeated timing, i.e., t1, t3, t4, t6, the next t1, t3, t4, t6... There is a method of obtaining an average value for one cycle) and detecting an effective value.

[Second Embodiment]
A sine wave power supply device including the sine wave effective value detection device of the first embodiment will be described as a second embodiment.

  The embodiment of FIG. 2 is a sine wave power supply device using an inverter, which will be described below based on FIG. 2, but is not limited to FIG. 2, and the present invention can output a sine wave, and Any power source can be used as long as its output is specified by an effective value and can be controlled to be the specified effective value.

  In FIG. 2, L1 and C1 constitute a filter and allow an input DC voltage to pass therethrough and prevent harmonic components generated in the switching circuit 11 from leaking to the input side. The MOSFETs Q5, Q6, Q7, and Q8 are used as switching functional elements and are driven by the drive circuit 19 with a high-frequency, for example, 150 KHz PWM signal. The filtering circuit 12 is a filter for receiving a switching waveform from the MOSFETs Q5, Q6, Q7, and Q8 and allowing only a desired sine wave frequency component to pass through and output.

There are, for example, a differential method and a polarity switching method for driving the MOSFETs Q5, Q6, Q7 and Q8. In the following description, the frequency of the desired sine wave and the PWM signal from the drive circuit 19 will be described as 50 Hz (half cycle: 10 mS), 150 kHz, for example. In the case of the differential method, as shown in FIG. 3A, the switching operation is performed with a PWM signal of 150 kHz. When the MOSFETs Q5 and Q8 are ON, the MOSFETs Q6 and Q7 are turned OFF and the MOSFETs Q5 and Q8 are turned ON. When Q is OFF, MOSFETs Q6 and Q7 are controlled to be ON. When outputting a half cycle in the positive direction of the sine wave, the ON duty of the MOSFETs Q6 and Q7 is increased in accordance with the sine wave, and when outputting a half cycle in the negative direction of the sine wave, the MOSFET Q5 and The ON duty of Q8 is controlled so as to increase in accordance with the sine wave. When the sine wave is close to zero, the ON / OFF duty of MOSFETs Q6 and Q7 and Q5 and Q8 are the same (refer to FIG. ) Further, the ON / OFF duty of the 150 kHz component is reversed in phase between MOSFETs Q5 and Q8 and MOSFETs Q6 and Q7. Therefore, the output voltage Vout is expressed by the following expression 3.
(Expression 3) Output voltage Vout =
Input voltage Vin × {Ton1 (Q7,6) −Ton2 (Q5,8)} / Ts
However, Ts = Ton1 + Ton2 (1 / Ts = 150 kHz)

  According to Equation 3, if driving is performed with a duty of Ton1 = 80% and Ton2 = 20%, the input voltage Vin needs to be 235V in order to output the AC100V sine wave voltage (141V in peak value). However, if Ton1 = 90% and Ton2 = 10%, Vin = 176V, and if Ton1 = 95% and Ton2 = 5%, the duty can be lowered to Vin = 157V. That is, the higher the duty, the better the efficiency.

Further, the polarity switching system for driving the MOSFETs Q5, Q6, Q7 and Q8 in FIG. 2 will be schematically described. In this case, MOSFETs Q5, Q6, Q7, and Q8 are driven by the signals shown in FIG. MOSFETs Q5 and Q7 are driven by a PW modulation signal of 150 kHz alternately every 10 mS. As a result, the output voltage Vout is expressed by the following equation 4. The waveform signal shown in FIG. 3B is generated and driven by the pulse width modulation means 18 and the drive circuit 19.
(Expression 4) Output voltage Vout =
Input voltage Vin x Ton (Q5, 7) / Ts
However, Ton (Q5, 7) / Ts (1 / Ts = 150 kHz) is PW
This is equivalent to the duty of the M modulation signal.

  With this polarity switching method, Vin = 201V or higher is required to output 141V at a duty of 70%, and Vin = 168V or higher is required to output 141V at a duty of 84%. . As in the differential type, the higher the duty, the higher the efficiency. For this purpose, a drive signal having a high duty even at 150 kHz is required from the drive circuit 19.

  The filtering circuit 12 includes a coil L2 and a capacitor C2, and has a constant that allows a 50 Hz sine wave to pass through and blocks a 150 kHz component.

  The current extraction means 13 in FIG. 2 is for extracting the output current in order to measure the output current of the sine wave, and is picked up at a known low-resistance inter-terminal voltage or the primary side of the transformer. It is taken out as the voltage across the terminals of a known resistor connected to.

  The level interface 14 converts the output voltage (for example, effective value 100V) of the filtering circuit 12 and the extracted voltage of the current extracting unit into the amplitude of the optimum operating range (for example, within 5V) of the sampling unit 15 at the next stage. Conversion is performed by changing the amplitude using a voltage divider or an operational amplifier, and / or changing the offset. The example corresponds to the “input sine wave” in FIG. In this figure, Vs corresponds to the offset.

  The sampling means 15 includes an ADC 15a (ADC is an analog-digital converter) as sampling means for output voltage detection, and an ADC 15b as sampling means for current detection. As described above, the ADC 15a and the ADC 15b repeat the index 8, 16, 24, 40, 48, and 56 corresponding to the repetition of the timings t1 to t6 shown in FIG. 8 of the previous period becomes 8 after passing the index 64 of the previous period.), And the extracted voltage and output voltage output from the level interface are sampled at those timings. The sampling means 15 in FIG. 2 corresponds to the sampling means 2 in FIG.

  The calculation means 16 receives the output voltage sampled by the sampling means 15, for example, L1, Lm, L2, L3, L4, Ls shown in the sampling waveform of FIG. The result is output. The computing means 16 in FIG. 2 corresponds to the computing means 3 in FIG.

  In the above formulas 1 and 2, the average value is an effective value, but the switching circuit 11 in FIG. 2 contains a high frequency, for example, 150 kHz AC component, and these cannot be dropped by the filtering circuit 12. (Refer to FIG. 4 or FIG. 5), and these are input to the sampling means 15 as ripples or noises. To prevent these effects, it is preferable to take an average value. The inductors of the coils L2 to L4 of the filtering circuit 12 may change depending on the output current, which may cause distortion in the sine wave of the output. In this case, it is preferable to use the average value corrected by Equation 2 above. Since the distortion is generated constantly in the coil, the distortion is constantly generated. Therefore, k in the correction term k (Lm−Ls−2Vp) of Equation 2 can be determined empirically.

The control means 17 performs PID (P: Proportionai proportional, I: Integral integral, Differential differentiation) control that is often used recently. This is proportional control that performs control based on deviation information from the effective value of the desired output that is the target value of control, integral control that performs control based on accumulated information of deviations in previous control, The differential control is performed based on the differential information of the deviation obtained from each deviation at the time of control and the previous control immediately before that. The deviation information, the accumulated information, and the differential information are obtained from the effective values at the time of each computation obtained by the computing means 16. The control means 17 adds control amounts of these proportional control, integral control and differential control, and instructs the pulse modulation means 18 to perform feed control. The control means 17 has a control mode as described below in combination with the calculation by the calculation means 16 in order to determine the timing of the control instruction.
(A) Control once per cycle. The effective value of the output voltage immediately before the control is detected for one period, and each control amount is obtained and controlled using the average value according to Equation 1 or the average value corrected according to Equation 2.
(B) Control is performed at each timing immediately after timing t1, when sampling means 15 samples the effective value of the output voltage, immediately after t3, immediately after t4, and immediately after t6 (hereinafter, this is repeated). That is, at each sampling timing, each control amount is obtained and controlled with the average value according to Equation 1 or the average value corrected according to Equation 2 for the immediately preceding cycle.
(C) Considering calculation timings other than the above (a) and (b), for example, calculating an average value every half cycle of a sine wave (two sampling timings) and controlling at a timing after the calculation Control timing can also be employed.

  The above (b) uses the average value for one period immediately before the control, and therefore the detection accuracy of the effective value is good. Further, the calculation of the average value before the control does not slow down the calculation because the oldest sampling value is discarded from the average value used for the previous control and the newest sampling value is added. Further, since the control is performed at each sampling timing, the control can be performed following the load fluctuation during that time. In addition, in order to calculate and control at each timing, it is assumed that a 50 Hz sine wave is generated with 64 data, and effective value detection including calculation is performed in a time of 20 ms / 64 = 312.5 μs or less. Can be achieved by the present invention. Therefore, the above (b) is recommended here. The arithmetic means 16 and the control means 17 can be constituted by a low-cost CPU and software. If only the effective value of one period is to be obtained, the calculation need only be completed by the next timing, so that a calculation of 2.5 ms or less is sufficient.

  Further, although the control means 17 performs PID control, only proportional control (P control) may be used depending on the purpose and accuracy of the control.

  Normally, proportional control is performed once in one cycle according to the above (a), but the error is checked once at timings t1, t3, t4, and t6. For example, a load change occurs after t3. The configuration may be such that only when the error exceeds a predetermined threshold in the single check at t4, the error is eliminated based on the error at t4.

  The pulse modulation means 18 controls the pulse width of 150 kHz as shown in FIG. 3 according to the control amount sent from the control means 17 and at the instructed timing.

  The drive circuit 19 receives the PWM wave of 150 kHz component from the pulse modulation means 18 and generates each rectangular wave of 50 Hz component including the PWM wave as shown in FIG. Control.

  As already described, the timing signal generation means 20 is a timing signal (the above index or repetition of t1 to t6) sampled by the sampling means 15, a 150 KHz component pulse signal used by the pulse width modulation means 18, and a drive circuit. A rectangular wave signal of 50 Hz component used by 19 is generated and sent. These may be separated and synchronized but may be configured independently, or may be incorporated in each of the sampling unit 15, the pulse width modulation unit 18, and the drive circuit 19.

  In the second embodiment, the inverter-type power supply device as shown in FIG. 2 has been described. However, any other method may be used as long as the device outputs a sine wave voltage. That is, in FIG. 2, the switching circuit 11 functions as a DC-AC voltage conversion means, and the switching circuit 11, the drive circuit 19, and the pulse width modulation means 18 function as variable means for varying the output voltage. Yes. Therefore, instead of these, there is a device that originally outputs a sine wave voltage, and if there is a variable means for changing the output voltage, the sine wave effective value detecting device of the present invention is provided and the sine wave effective value is provided. The voltage can be stably controlled and output.

[Example of effective value detection in sine wave effective value detector]
Effective value by the sine wave effective value detection device of the first embodiment or the sine wave effective value detection device constituted by the level interface 14, the sampling means 15, the calculation means 16 and the timing signal generation means 20 of the second embodiment. An example of the measurement is shown in FIG. As shown in “Measurement count (cycle)” in FIG. L1 to L4 in FIG. 6 are the same as L1 to L4 illustrated in FIG. The measurement timing is also the same as in FIG. The “average value” in FIG. 6 is a value obtained by the above equation (1). Note that L1 to L4 and the average value are indicated by dots. This is due to digital processing, and is a value when the entire measurement range of the amplitude on the vertical axis in FIG. 1B is measured as 1024 dots. 125 dots corresponds to an effective value of 100V. The “detection voltage” in FIG. 6 is obtained by converting the “average value” into a voltage, and this is an effective value measured.
From FIG. 6, it can be understood that the fluctuation of the effective value of the sine wave input in FIG. 1 (in FIG. 2, the sine wave output from the sine wave power supply device) can be detected.

[Control Example of Second Embodiment]
FIGS. 4A, 4B, 4C, and 4D show control examples when a sine wave effective value voltage of about 100 V is output in the configuration of FIG. 4 (A) and 4 (B) are diagrams showing the start-up characteristics. FIG. 4 (A) shows a rising voltage waveform when starting with no load (output current is zero) and is almost stable from the first cycle. A voltage waveform is shown. FIG. 4B shows a rising voltage waveform in the case of starting up with a load of 0.5 A. The output voltage of the first one cycle is lower, but after that, an almost stable voltage waveform is shown. 4 (C) and 4 (D) are diagrams showing response characteristics at the time of load change after startup. FIG. 4 (C) is a voltage waveform when the load is suddenly changed from a state of 0.5 A to a no-load state. The first one cycle after that changes somewhat to a higher voltage, but after two cycles, a stable voltage waveform is shown. FIG. 4 (D) shows a voltage waveform when the load is suddenly changed from the no-load state to the load 0.5A state. The first one cycle fluctuates to the lower side, but a stable voltage waveform is obtained from the next cycle. Show.

  5 (A) and 5 (B) are diagrams showing response characteristics at the time of load change after start-up as in FIGS. 4 (C) and 4 (D), and are examples observed in more detail. FIG. 5A shows a voltage waveform when the load state is suddenly changed from a load state to a no-load state, and the voltage waveform immediately after the sudden change somewhat fluctuates to a higher level. Is back to FIG. 5B shows a voltage waveform when the voltage is suddenly changed from the no-load state to the load state. The voltage immediately after the sudden change decreases, but immediately after the voltage decreases, the voltage waveform returns to the original voltage waveform. These are because the response of the sine wave effective value detection device is fast and control is performed for each timing signal.

  4 and 5, according to the present invention, it is possible to suppress voltage fluctuation between sampling timings at an early stage within one cycle.

[Example of correction of distortion in effective value]
In FIG. 4 and FIG. 5, the load current is turned on / off to change, and the effective value of the output voltage is detected and controlled to be constant, but the steady peak voltage is as described above. It differs due to the influence of the coil of the filter. In an actual example, if the design value is 98 V output (the peak value at this time is 689 dots when represented by dots as shown in FIG. 6), it is almost the same as the design value at no load, but the load is 0.5 A. Then, the peak value becomes 702 dots, and the effective value becomes 102.6 V (102.6 / 98 = 1.007). Therefore, when the peak voltage is larger by 13 (702-689) dots, the correction value according to the correction term in Expression 2 is 125 × 0.047 (125 is the number of dots corresponding to 100 V) = 6 dots (125 dots: By controlling 131 (equivalent to 104.8 V) in addition to 100 V as an effective value, fluctuations in the output voltage can be corrected.

It is a figure which shows the function structure and timing of the sine wave effective value detection apparatus as 1st Embodiment based on this invention. It is a figure which shows the function structure of the sine wave power supply device as 2nd Embodiment. It is a figure for demonstrating the switching operation | movement in FIG. It is a figure for demonstrating the example of control of the output voltage of 2nd Embodiment. It is a figure for demonstrating the example of control of the output voltage of 2nd Embodiment. It is a figure which shows the example of an effective value detection of a sine wave effective value detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Timing signal generation means 2 Sampling means 3 Calculation means 11 Switching circuit 12 Filtering circuit 13 Current extraction means 14 Level interface 15 Sampling means 16 Calculation means 17 Control means 18 Pulse width modulation means 19 Drive circuit 20 Timing signal generation means

Claims (4)

A plurality of timing signals in which the absolute value of the amplitude of a sine wave signal of a predetermined cycle as a detection target is the same value as the effective value of the sine wave signal within one cycle, and the maximum within one cycle of the target sine wave and timing signal generating means for generating a timing signal as a timing signal and the minimum value becomes a value at each timing signal output from said timing signal generating means, sampling means for sampling the received sine wave signal, said plurality calculates the average value of the absolute value of the amplitude obtained by sampling based on the timing signal, the difference between the values with each other obtained by sampling based on two timing signals which becomes the maximum value and the minimum value the mean value is corrected according to the difference between twice the amplitude value of the sine wave to the target, the effective value of receiving said corrected average value sinusoidal signal And arithmetic means for outputting Te, sinusoidal effective value detecting apparatus characterized by comprising. Variable means for variably outputting the voltage of the sine wave, a plurality of timing signals in which the absolute value of the amplitude of the desired sine wave signal becomes the same value within one cycle as the effective value of the sine wave signal, and the desired signal and timing signal generating means for generating a timing signal as a timing signal and the minimum value becomes the maximum value in one period of a sine wave at each timing signal output from said timing signal generating means, said variable means outputs Sampling means for sampling voltage, and calculating an average value of absolute values obtained by sampling based on the plurality of timing signals, and sampling based on the two timing signals having the maximum value and the minimum value The average value is corrected in accordance with the difference between the obtained values and twice the target sine wave amplitude value, and the corrected average value is calculated. Calculating means for force, the effective value of said calculating means is outputted, the sine wave power supply, characterized in that a control unit for varying relative to said varying means so that the effective value of the desired sine wave apparatus. A switching means for converting the alternating current by switching a pulse of a predetermined period upon receiving the DC voltage, a filter for converting a sine wave and smoothing the output of said switching means, the absolute value of the amplitude of the desired sine wave that A timing signal for generating a plurality of timing signals having the same value within one cycle as the effective value of the sine wave signal, and a timing signal having the maximum value and a timing signal having the minimum value within one cycle of the desired sine wave a generation unit, each timing signal output from said timing signal generating means, sampling means for sampling the voltage the filter output, the absolute value of the amplitude obtained by sampling based on the plurality of timing signals It calculates the average value, based on two timing signals which becomes the maximum value and the minimum value sampled The average value is corrected according to the difference between the obtained values and twice the target sine wave amplitude value, and the corrected average value is the effective value of the received sine wave signal. And a control unit for controlling the output voltage of the filter to be an effective value of the desired sine wave by changing the width of the pulse based on the effective value output by the calculating means. And a sine wave power supply device. The plurality of timings are four timings,
The control unit calculates the effective value calculated based on the values sampled by the four timing signals and the two timing signals that are the maximum value and the minimum value in one cycle immediately before the control from the calculation unit. 4. The sine wave power supply device according to claim 3 , wherein after receiving, the output voltage of the filter is controlled to be an effective value of the desired sine wave.

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