JPH0678564A - Controller of multiphase power converter - Google Patents

Abstract

(57) [Summary] [Purpose] In a large-capacity self-exciting power converter using a transformer, control is performed to detect an eccentricity current component from the excitation current of the transformer and cancel it. A control device for a multi-phase power converter according to the present invention includes an exciting current detection circuit 10 for detecting an exciting current of each phase of a transformer 4.
1 and the detection output of the exciting current detection circuit 101,
Excitation current compensating circuit 2 for compensating the offset component included in the detection output and the component caused by the imbalance of the power supplies of the respective phases
01, a reference pulse generating circuit 32 for generating a reference pulse signal for PWM controlling the power converter 21, and an output signal of the exciting current compensating circuit 201, and when a biased magnetic state is detected from this output signal. Is a bias magnetic compensation circuit 30 that corrects the pulse width of the reference pulse signal according to the bias amount.
1 and.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for a multi-phase power converter that supplies AC power to a load via a transformer,
In particular, the present invention relates to a control device for a power converter that is suitable in the field of using a power converter that requires a large capacity.

[0002]

2. Description of the Related Art As a bias magnetic suppression control method for a transformer used in a multi-phase power converter such as an inverter, there is a method for correcting a DC component of a voltage command value according to an average value of one cycle of an exciting current. Normally, the integrated result of one cycle of the exciting current is zero, but when the magnetic bias occurs, the bias current component is superimposed and does not become zero. The DC component of the voltage command value is adjusted in the direction of reducing the eccentric current according to the polarity of the integration result. An example of this is JP-A-64
There is a device as disclosed in Japanese Patent No. 5365.

Further, there is a method in which the maximum positive and negative current values in the vicinity of the maximum transformer magnetic flux density are sample-held and the amount of magnetic bias is detected from the difference between the two. As an example of this, Japanese Patent Laid-Open No.
There is a device as disclosed in Japanese Patent Publication No. 93475.

[0004]

Problems to be Solved by the Invention JP-A-64-5365
In the conventional device described in Japanese Patent Laid-Open Publication No. 2003-242242, the detection of the amount of magnetic bias is detected by integrating the current for one cycle, so that the offset including the detector is integrated over one cycle. The current detector detects the current including the load current and the exciting current. Usually, the ratio of the exciting current to the load current is very small and is about several% to 10%. Therefore, there is a problem in that the offset amount cannot be ignored with respect to the exciting current to be detected, and the accuracy of the bias magnetism detection deteriorates.

Further, in the conventional apparatus disclosed in Japanese Patent Laid-Open No. 3-93475, the positive and negative maximum values of the exciting current are sample-held, so if the current instantaneous value is erroneously detected due to noise or the like, a very large deviation will occur. It is considered that magnetism occurred. In this case, an incorrect detection signal is input to the bias suppression control circuit, and the normal bias suppression operation is not performed.

The present invention has been made in view of such circumstances, and it is possible to reduce the influence of the offset of the current detector for detecting the exciting current of the transformer and prevent the erroneous detection due to noise. An object of the present invention is to provide a control device for a container.

[0007]

A control device for a multi-phase power converter according to the present invention is a control device for a multi-phase power converter, which converts AC power into DC power and supplies the DC power to a load via a transformer. The excitation current detection means for detecting the excitation current of each phase of the transformer and the detection output of the excitation current detection means of each phase of the transformer are taken in, and the offset component contained in the detection output and the power supply failure of each phase. Exciting current compensating means for compensating a component caused by balance, pulse signal generating means for generating a reference pulse signal for PWM control of the power converter, and output signal of the exciting current compensating means, and the output signal And a bias magnetic compensating means for correcting the pulse width of the reference pulse signal according to the bias amount when the bias magnetic state is detected.

Further, in the control device for a multi-phase power converter of the present invention, the exciting current compensating means calculates a value proportional to the sum of the exciting currents of the respective phases detected by the exciting current detecting means from the exciting currents of the respective phases. It is characterized by having means for subtracting.

Further, in the control device for a multi-phase power converter of the present invention, the bias magnetizing compensating means integrates the exciting current output from the exciting current compensating means and the phase detecting means for detecting the reference phase of each phase. Integrating means, sample-hold means for sampling and holding the integrated output of the integrating means, and the integrating means at the midpoint of the period when the positive reference pulse signal is output based on the detection output of the phase detecting means. Reset signal generating means for generating a reset signal for resetting,
Sample hold signal generating means for generating a sample signal for performing the sample hold operation of the sample hold means at the time of falling of the first reference pulse signal of the plurality of positive side reference pulse signals. And

Further, in the control device for a multi-phase power converter of the present invention, the bias compensating means outputs the power converter in a direction opposite in polarity to the direction of bias generation so as to cancel the generated bias. So that the correction pulse is added to or subtracted from the reference pulse signal output from the pulse signal generation means so as to be adjusted.

Further, in the control device for a multi-phase power converter according to the present invention, the bias magnetic compensation means corrects the pulse width of the reference pulse signal for a plurality of positive side and negative side reference pulse signals in one cycle. It is characterized in that it has a second pulse width correcting means for performing a period limited to the trailing edge of the last reference pulse.

[0012]

In the controller of the multi-phase power converter having the above structure, the exciting current of each phase of the transformer is detected by the exciting current detecting means, and the detected output of the exciting current detecting means of each phase of the transformer is detected. The included offset component and the component caused by the imbalance of the power supplies of the respective phases are removed by the exciting current compensating means. When a bias magnetic state is detected from the output signal of the exciting current compensating means, the bias width compensating means corrects the pulse width of the reference pulse signal generated by the pulse signal generating means according to the bias amount.

In the control device for the multi-phase power converter having the above structure, the reference phase of each phase is detected by the phase detecting means.

Further, the reset signal generating means generates a reset signal for resetting the integrating means at the midpoint of the period in which the positive reference pulse signal is output based on the detection output of the phase detecting means. Then, based on the reset signal, the exciting current output from the exciting current compensating means is integrated by the integrating means.

Further, the sample and hold signal generating means generates a sample signal for performing the sample and hold operation of the sample and hold means at the time of falling of the first reference pulse signal of the plurality of positive side reference pulse signals. . The integrated output of the integrating means is sampled and held by the sample and hold means based on the sample signal.

Therefore, the influence of the offset of the current detector for detecting the exciting current of the transformer connected to the output side of the power converter can be reduced, and erroneous detection due to noise can be prevented.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an embodiment of a control device for a multiphase power converter according to the present invention. In the figure, the AC power output from the AC power supply 1 is converted into DC power by the converter 2, returned to AC power by the power converter 21, and then supplied to the load 5 via the transformer 4. The control device according to the present invention includes a magnetic bias suppression control circuit 10, a control circuit 31, a reference pulse generation circuit 32, and a gate pulse generation circuit 33.

By the way, the capacitor 3 is connected between the load 5 and
Since the DC voltage, which is the voltage across the capacitor 3, fluctuates by charging and discharging through the power converter 21 and the transformer 4, the output voltage is adjusted by the converter 2 or the DC voltage is adjusted by the control circuit 31. There is a need. Therefore, the control circuit 31 takes in the voltage between the terminals of the capacitor 3 directly, takes in the input voltage of the load 5 from the instrument transformer 8, and takes in the current supplied to the load from the instrument current transformer 7 to obtain the respective voltages. Control the value.

Further, the control circuit 31 outputs the command of the voltage V * to be applied to the load and the phase difference command φ * from these detected values. The reference pulse generation circuit 32 supplies ON / OFF pulses for obtaining a desired output voltage from V * and φ * to the power converter.

The control device for a multi-phase power converter according to the present invention has a bias magnetizing suppression control circuit 10 for suppressing bias magnetizing of the transformer provided on the output side of the power converter (inverter) 21. There is. i1 and i2 are the load side current and the converter side current, respectively. Here, the load side is defined as primary and the converter side is defined as secondary. The current on the converter side is detected by the instrument current transformer 6. The bias magnetic suppression control circuit 10 receives the gate pulse switching angle information θP and θN in addition to the currents i1 and i2, and receives the reference signal Sy of each phase.

At the time of occurrence of magnetic bias, pulse width corrected switching angle information θP ', θN' is output. The gate pulse generation circuit 33 generates a gate pulse to be supplied to the power converter 21 based on the pulse width-corrected switching angle information θP ′ and θN ′ from the magnetic bias suppression control circuit 10.

Next, FIG. 3 shows a specific configuration of the magnetic bias suppression control circuit 10. In the figure, the exciting current detection circuit 101 is composed of circuit configurations 1011 1012 1013 for three phases, and detects the exciting current of each phase. Exciting current detector 101
In 1, the excitation current i0U is calculated from the ampere-turn difference between the primary current i1U and the secondary current i2U of the U-phase transformer for one bridge.
Is output. If the secondary conversion current of i1U is i1U ', the exciting current i0U can be obtained by subtracting i1U' from i2U. Similarly, for the V phase and the W phase, i0v, i
Ask for 0w. The detector unbalance compensation circuit 201 compensates for the imbalance between the three phases and the offset of the operational amplifier or the like during current detection. Add the exciting currents i0U, i0v, i0w of each phase to the adder 2
The result obtained by averaging in 011 and averaging the three phases in the averaging circuit 2012 is given to the subtractors 2013, 2014 and 2015, and the excitation currents i0U ', i0v', i0 from which noise on the circuit is removed
get w '

Next, in the magnetic bias compensating circuit 301, the magnetic bias compensating circuit 301 for each phase for each cycle of the exciting current for each phase.
1, 30, 12 and 3013 perform bias magnetic compensation and pulse width correction.

Next, the operation of the magnetic bias suppression control will be described. Figure 4
3 shows a specific configuration of the bias compensating circuit in FIG. 3, and FIG. 2 shows operation waveforms of each circuit in FIG. 1, FIG. 3, and FIG. With reference to these drawings, the operation will be described mainly focusing on the U phase. For example, if the voltage waveform v as shown in FIG. 2A is output from the reference pulse generation circuit 32 and applied to the winding of the transformer, the magnetic flux density B is integrated with v, and the waveform as shown in FIG. Becomes When the magnetism is not generated in the iron core, the exciting current waveform i0 has a waveform substantially similar to that of FIG. 2 (b). When the demagnetization occurs, the exciting current becomes excessive in the first part where the magnetic flux density B reaches the peak value, and
The current waveform is as shown in (c). The portion marked with a circle in this figure shows the case where the magnetic field is biased to the positive side. In the voltage waveform, an eccentric current is likely to occur near the last portion θP of the continuous positive voltage pulse and near the final portion θN of the continuous negative voltage pulse.

Therefore, since the magnetic flux deviation of the transformer can be detected, the magnetic flux is almost proportional to the exciting current. Therefore, it can be achieved by measuring the positive and negative imbalance for one cycle of the exciting current i0 of each phase. That is, one cycle of the exciting current i0 of each phase is integrated. The magnetic bias can be suppressed by adjusting the pulse width in the direction in which the polarity of the value of the integration result is canceled. The operation will be specifically described.

FIG. 2D shows the U-phase reference signal Syu. The phase detector 3021 of the U-phase bias magnetic compensation circuit 3011 detects the phase based on the U-phase reference signal Syu, and the reset signal generator 3022 outputs the U-phase integral reset signal (see FIG. 2).
(E)) is obtained. The generation phase of the U-phase integral reset signal is generated at each midpoint of two positive-side pulses of the reference pulse of the voltage waveform of FIG.

Further, a sample hold signal generator 3023
Obtains the U-phase sample signal (FIG. 2 (g)). The generation phase of this U-phase sample signal is generated at the time of the falling edge of the pulse before the two positive side pulses of the reference pulse of the voltage waveform of FIG.

The P multiplication reference generator 3024 obtains the P multiplication signal (FIG. 2 (k)). This P-multiplied signal has a limited time width tw centered on the trailing edge of the pulse after the two positive-side pulses of the reference pulse of the voltage waveform (FIG. 2A), and the value is "1". It is a pulse.

The N multiplication reference generator 3025 obtains the N multiplication signal (FIG. 2 (l)). This N-multiplied signal has a limited time width tw centered on the trailing edge of the pulse after the two negative-side pulses of the reference pulse of the voltage waveform (FIG. 2A), and the value is "1". It is a pulse.

The integrator 3026 integrates the excitation current i0U 'signal from the U-phase reset signal to the next U-phase reset signal. FIG. 2F shows the integration result. Figure 2
When there is a demagnetization as in (c), the result of one-cycle integration does not become zero, and the integrated value remains for h. The remaining integrated value h is stored in the sample hold unit 3027 as a sample signal generated by the sample hold signal generator 3023.

The integral correction amount SH (FIG. 2 (h)), which is the output signal of the sample hold device 3027, is held until the sample signal output at the next timing.

Next, in the gain elements 3028 and 3029, the pulse correction widths ΔθPu and ΔθNu are obtained from the integral correction amount SH. The reason that the gain characteristics are left / right reversed between 3028 and 3029 is that the pulse width correction direction for suppressing the eccentricity current has an opposite relationship between the positive side pulse and the negative side pulse. Since SH> 0, the phase compensation amount ΔθPU becomes ΔθPU <0 by the gain elements 3028 and 3029 (see FIG. 2).
(I)), the phase compensation amount ΔθNU is ΔθNU> 0 (Fig. 2
(J)).

The multiplier 3030 has a phase compensation amount of Δθ PU and P
The switching angle θPU of the reference pulse voltage output from the reference pulse generation circuit 32 in the period immediately after the period in which the bias signal is generated by multiplying the multiplication signal is corrected by ΔθPU at the timing synchronized with the P multiplication signal to obtain the switching angle. θP becomes smaller.

The phase compensation amount of the multiplier 3031 is ΔθNU
The switching angle θNU of the reference pulse voltage output from the reference pulse generation circuit 32 in the period immediately after the period in which the magnetic field is generated by multiplying the N multiplication signal with N is corrected by ΔθNU at the timing synchronized with the N multiplication signal, The switching angle θNU becomes large. That is, the adder 3032 outputs θ
PU and ΔθPU are added to obtain θPU '. Also, the adder 30
33 adds θNU and ΔθNU to obtain θNU ′.

In the example of FIG. 2 (m), since the eccentricity current indicated by ◯ is in the positive direction, after detecting the eccentricity, the positive pulse width is narrowed and the negative pulse width is widened as follows. The period θP,
It is reflected in θN, and the bias magnetic current can be suppressed.

Similarly, the timing of V-phase bias magnetic control is V
The phase reset signal (FIG. 2 (n)) and the V phase sample signal (FIG. 2 (p)) are used. The timing of the W-phase bias magnetic control is the W phase reset signal (FIG. 2 (o)) and the W phase. It is performed by the sample signal (FIG. 2 (q)).

According to the present invention, since the accuracy of detecting the amount of bias magnetism can be increased, the present invention can be sufficiently applied to applications where a DC voltage is high.

The above embodiments can be realized by software processing using a microcomputer. In this case, the hardware for controlling the magnetic bias is not required, and the circuit configuration can be implemented by only adding a part of the software of the control device of the normal power converter.

[0039]

As described above, according to the present invention,
In order to control the magnetic bias of the transformer, integrate the exciting current for one cycle, and at the stage of detecting the exciting current, make sure that there is no error in integrating the exciting current due to imbalance, drift, offset, noise, etc. of each phase. Since the detector unbalance compensation circuit is also used in the above, the accuracy of the bias magnetic suppression control can be improved, and the power converter can be operated in a stable state.

Further, since the magnetic bias of the transformer can be suppressed with high accuracy, the magnetic flux density of the iron core can be designed higher and the size and weight can be reduced.

Further, since the overcurrent due to the magnetic bias can be suppressed, the overcurrent breakdown due to the magnetic bias of the semiconductor switch used in the power conversion circuit can be prevented. It is also easy to increase the capacity of the self-excited converter by multiplexing the transformers.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a control device for a multiphase power converter according to the present invention.

FIG. 2 is a waveform diagram showing an operating state of each unit of the control device for the multiphase power converter shown in FIG.

FIG. 3 is a block diagram showing a specific configuration of a magnetic bias suppression control circuit in FIG.

FIG. 4 is a block diagram showing a specific configuration of the bias compensation circuit in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Converter 3 Capacitor 4 Transformer 5 Load 6 Current detector 7 Current detector 8 Instrument transformer 10 Bias magnetism suppression control circuit 21 Power converter 31 Control circuit 32 Reference pulse generation circuit 33 Gate pulse generation circuit 101 Excitation Current detection circuit 201 Detector unbalance compensation circuit 301 Magnetic bias compensation circuit

Claims (5)

[Claims] 1. A control device for a multi-phase power converter that converts AC power into DC power and supplies the load to a load via a transformer, and an exciting current detecting unit for detecting an exciting current of each phase of the transformer. An exciting current compensating means for taking in a detection output of the exciting current detecting means of each phase of the transformer and compensating for an offset component contained in the detecting output and a component due to an imbalance of power supplies of each phase; Pulse signal generating means for generating a reference pulse signal for PWM control of the electric device, and an output signal of the exciting current compensating means, and when a bias magnetic state is detected from the output signal, the bias magnetic amount is changed to And a bias magnetic compensating means for correcting the pulse width of the reference pulse signal according to the control unit. 2. The exciting current compensating means has means for subtracting a value proportional to the sum of the exciting currents of the respective phases detected by the exciting current detecting means from the exciting currents of the respective phases. 1. The control device for a multiphase power converter according to 1. 3. The bias magnetization compensating means detects a reference phase of each phase, an integrating means for integrating the exciting current output from the exciting current compensating means, and an integrated output of the integrating means. Sample-hold means for sample-holding, and reset signal generating means for generating a reset signal for resetting the integrating means at a midpoint of a period in which the reference pulse signal on the positive side is output based on a detection output of the phase detecting means. A sample-hold signal generating means for generating a sample signal for performing a sample-hold operation of the sample-hold means at the time of falling of the first reference pulse signal of the plurality of positive-side reference pulse signals. The control device for a multiphase power converter according to claim 1, wherein the control device is a multiphase power converter. 4. The bias magnetic compensating means from the pulse signal generating means so that the output of the power converter is adjusted in a direction opposite in polarity to the direction of bias generation so as to cancel the generated bias. The control device for a multi-phase power converter according to claim 3, further comprising first pulse width correction means for adding / subtracting the correction pulse to / from the output reference pulse signal. 5. The bias magnetization compensating means limits the correction of the pulse width of the reference pulse signal based on the trailing time point of the last reference pulse of a plurality of positive side and negative side reference pulse signals in one cycle. The control device for a multi-phase power converter according to claim 4, further comprising a second pulse width correction means that performs the pulse width correction in a predetermined period.