JP2607471B2 - Control device of pulse width modulation power converter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device of a PWM converter, and more particularly to a configuration of a control device of a PWM converter suitable for a main circuit of an AC electric vehicle.

[Conventional technology]

In recent years, the development of power semiconductor devices has been remarkable, and power converters using such devices have been widely used from industrial use to home use.

Among them, AC-DC converters for converting AC power, which has been used for a long time, into DC power have a high penetration rate, and their capacities are increasing. However, in the conventional AC-DC converter, the AC input current contains many harmonics, and this causes an induction failure, which is becoming a serious social problem.

On the other hand, recent interest in energy saving is high, and in particular, improvement of power supply power factor is one of the major issues, and development of AC-DC converters with improved power factor is being promoted in various fields.

Against this background, a pulse-width-modulated power converter (hereinafter simply referred to as a PWM converter) is one of the devices that has recently been in the spotlight. In this PWM converter, if the switching frequency of the switching element can be sufficiently increased, an AC input current (hereinafter simply referred to as an AC current) supplied from the power supply to the converter can be made substantially sinusoidal. In addition, by adjusting the magnitude and phase of the input voltage on the AC side of the PWM converter (hereinafter referred to as the converter input voltage), the power supply power factor can be made almost unity. The feature is that an inverse conversion operation is also possible.

For example, the Institute of Electrical Engineers of Japan RAT-86-5 (Jan.
24), pp. 39-48.

[Problems to be solved by the invention]

However, in general, the performance of the PWM converter greatly depends on the performance of the switching elements constituting the PWM converter, and the AC current, the modulation frequency, and the like are limited. In particular, the current needs to be designed with a certain margin in consideration of the ripple current included in the AC current, and therefore, the current utilization of the switching element cannot be maximized.

SUMMARY OF THE INVENTION It is an object of the present invention to maximize the capability of a PWM converter by making it possible to supply the AC current of the PWM converter as much as possible within the range permitted by the switching element.

[Means for solving the problem]

An object of the present invention is to provide a pulse width modulation power converter that is connected from an AC power supply via a reactor and converts an AC to a DC and that can perform an inverse conversion operation, and a deviation between the DC voltage of the pulse width modulation power converter and its command value. Means for generating an AC input current command for the power converter, a current limiting means for limiting the value of the AC input current command to within a predetermined value, and a deviation between the output of the current limiting means and the actual AC current. Means for generating a command of an imaginary axis component of the input voltage of the pulse width modulated power converter based on the pulse width modulated power converter based on the deviation between the phase difference between the voltage and current of the AC power supply and the command value. Means for generating a command of a real axis component of the input voltage of the converter, and a pulse width modulated gate for inputting the command of the imaginary axis component of the input voltage and the command of the real axis component of the input voltage and supplying the command to the pulse width modulation power converter Signal Means for generating a pulse width modulated power converter, wherein the current limiting means sets the predetermined value to the peak value when the peak value of the alternating current of the pulse width modulated power converter is equal to or greater than a predetermined value. This is achieved by having means for narrowing down in response to

[Action]

With this configuration, when the DC voltage fluctuates due to load fluctuation or power supply voltage fluctuation and the output of the DC voltage regulator exceeds a set value, the DC voltage is regulated by a limiter provided at the output of the DC voltage regulator. Limiting the output of the current regulator,
Limit the imaginary component of the converter input voltage.

Also, if a minor ACR is provided after the limiter, the converter input current itself will be limited.

Furthermore, by adjusting the limiter value according to the peak value of the AC input current of the PWM converter, the AC current can be flowed to the limit of the allowable range of the breaking current of the switching element, and the current utilization rate of the switching element can be increased. Can be.

〔Example〕

 FIG. 1 shows a reference example for implementing the present invention.

Main circuit unit composed of GTO thyristors G ₁ ~G ₄ connected in antiparallel with the diode D ₁ to D ₄ having a self-extinguishing function is connected to an AC power source via an AC reactor ACL, the DC load side Is connected to a smoothing capacitor.

On the GTO thyristor, and controls the off-control device for controlling the output power and power factor of the PWM converter, a command value E _d * and the feedback value deviation epsilon _ed from the converter input voltage and E _d of DC voltage real axis of the imaginary part setting unit IPS for calculating creating imaginary axis component I _{m {C},} the AC power source voltage and the phase command value phi * and the converter input voltage from the deviation epsilon _phi between the feedback value phi of the alternating current Real part setting part RPS for calculating and creating the component _Re { _C }
When the amplitude command converter input voltage by polar coordinate transformation to R _{e {C}} and I _{m {C} |} C | and coordinate converter PCV and creating a phase command theta | _{C |} and is pulse width modulated by theta It comprises a gate pulse generator GPG that generates a gate pulse.

The imaginary part setting unit IRS is a DC voltage regulator AVR that creates an AC current command I _SO * using the DC voltage deviation ε _ed as an input.
And an output limiter LMT, an AC current regulator AC that calculates and outputs an imaginary axis component I _m { _C } of the converter input voltage from a deviation ε _iS between the limiter output I _S * and the AC current feedback value I _S.
Consists of R. On the other hand, the real part setting unit RPS determines the phase difference φ between the AC power supply voltage and the AC current detected by the phase detector PHD.
And a power factor adjuster PFR for calculating and creating a real axis component R _e { _C } of the converter input voltage from the deviation between the phase difference command φ * and the phase difference command φ *. Here, normally, in order to keep the power factor at 1, φ * is set to 0 ° during forward conversion and 180 ° during reverse conversion.

FIG. 2 shows a vector diagram of voltage and current when the PWM converter is operated at a power factor of 1. As shown in the figure, the converter input voltage _C is usually adjusted so that the power supply voltage _s and the voltage _L (= _S − _C ) applied to the AC reactor ACL are orthogonal to each other, so that the power supply voltage _S and the AC current _S are in phase. Is controlled so that

Generally, the alternating current _S can be expressed by the following equation.

As apparent from the above equation, if the reactance L of the power supply angular frequency ω and an AC reactor is constant, the AC by adjusting the imaginary axis component I _{m {C}} of the converter input voltage and current
The real axis component (effective component) of _S can be adjusted, and by adjusting the real axis component R _e { _C } of the converter input voltage, _S
Imaginary axis component (ineffective component) can be adjusted. Therefore, I
while adjusting the effective current (power adjustment) with _{m {C},} enables the adjustment of the power factor at R _{e {C}.}

By the way, the PWM converter has an upper limit of the modulation frequency determined by the minimum on-time or the minimum off-time of the switching element (generally determined by the minimum off-time). Instead, the waveform includes a ripple as shown in FIG. Since the peak value I _{the speak} of the alternating current corresponding to the maximum cut-off current of the switching-element (maximum value of the current switching-element is blocked), PWM scope I _{the speak} does not exceed the allowable value of the cutoff current of the switching-element It is necessary to operate the converter.

Now, consider the case where the DC voltage E _d is decreased by variation of the load LOAD. At this time, the DC voltage regulator AVR increases the AC current command _ISO * to keep the DC voltage constant.
When this command value I _SO * reaches a limiter value I _SL of a limiter LMT set in advance so that a peak value I _speak of an alternating current corresponding to the maximum breaking current of the GTO does not exceed a specified value,
The AC current command value I _S * is limited to I _SL to limit _Im { _C }.

In the past, the AC current I _S can be supplied from the power supply up to the limiter value I _SL , so that there is no need to allow the AC current unnecessarily as in the related art, and the power that can be converted is expanded.

If an overcurrent occurs due to a failure such as a load short circuit, a countermeasure such as operating an overcurrent detector (not shown) to shut off the GTO and then stop the operation may be considered.

FIG. 4 shows an embodiment of the present invention. In this example,
The value of the alternating current peak value I _{the speak} that have been conducted under the detected alternating current peak value detector IPD, change the Rimitsuta LMT Rimitsuta value I _SL provided on the output of the DC current regulator AVR using Rimitsuta value setter LMS The other points are the same as in the reference example shown in FIG.

FIG. 5 shows an example of the characteristics of the limiter value setting device LMS. Output I _SL of Rimitsuta value setter LMS is alternating current peak value began to decrease to reach I _SP1, a 0 in I _SP2. That is, the alternating current peak value I _{the speak} is when rises above I _SP1, Rimitsuta value I _SL are gradually narrowed down, alternating current instruction value I _S * is Rimitsuta operates when it reaches I _SL. Therefore, the peak value I _speak of the alternating current is limited to _ISP2 or less. Here, _ISP2 is set to be equal to or less than the operating current set value (I _OC ) of the overcurrent detector that operates at the time of overcurrent.

According to the present embodiment, the peak value of the AC current, that is, GTO
Since the maximum alternating current can be passed within the range where the cut-off current does not exceed the allowable maximum value, the PWM converter can expand the processing power to the maximum. Therefore, the device can be further reduced in weight and size.

〔The invention's effect〕

According to the present invention, since the input current of the PWM converter can flow up to the current value determined by the limiter value of the limiter provided at the output of the DC voltage regulator, the current utilization of the switching element can be increased. As a result, the maximum processing power of the PWM converter is increased by the increase in the current utilization rate of the element, which leads to a reduction in the weight and size of the device.

[Brief description of the drawings]

FIG. 1 is a diagram of a reference example for implementing the present invention, and FIG.
FIG. 3 is a diagram showing an alternating current waveform of the PWM converter when the PWM converter is controlled at a power factor of 1, FIG. 4 is a diagram showing an embodiment of the present invention, and FIG. FIG. 4 is a diagram illustrating an example of a characteristic of a limiter value setting device LMS. E _S … AC power supply voltage, I _s … AC current, E _C … AC input voltage of the converter, E _L … AC reactor voltage, E _d …
DC voltage, G ₁ ~G ₄ ...... GTO thyristor, D ₁ ~D ₄ ...... diode, ACL ...... AC reactor, C _d ...... smoothing capacitor, LOAD ...... load, IPS ...... imaginary part setting unit, RPS … Real part setting part, AVR… DC voltage regulator, LMT… Limiter, AC
R: AC current controller, PHD: Phase detector, PFR: Power supply power factor controller, PCV: Coordinate converter, GPG gate pulse generator, E _d *: DC voltage command value, ε _ed ... … DC voltage deviation, I _S *… AC current command value, ε _iS … AC current deviation,
phi * ...... phase angle command value, I _{m {C}} ...... converter input voltage imaginary axis component, R _{e {C}} ...... converter input voltage real axis component, theta ...... converter input voltage phase angle, | C _| ... …
Converter input voltage amplitude, is …… AC current, I _speak ……
AC current peak value, IPD …… AC current peak value detector, L
MS ...... Rimitsuta value setter, I _SL ...... Rimitsuta value.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshihiko Ishida 3-1-1 Sachimachi, Hitachi City Inside Hitachi Plant, Hitachi, Ltd. (56) References JP-A-58-79478 (JP, A) JP-A-58-79478 61-66569 (JP, A)

Claims (1)

(57) [Claims] A pulse width modulation power converter connected from an AC power supply via a reactor and capable of performing an inverse conversion operation for converting AC to DC, and a DC voltage of the pulse width modulation power converter and a command value thereof. Means for generating an AC input current command for the power converter based on the deviation, current limiting means for limiting the value of the AC input current command to within a predetermined value, and the output of the current limiting means and the actual AC current. Means for generating a command for the imaginary axis component of the input voltage of the pulse width modulated power converter based on the deviation; and the pulse width modulated power based on the deviation between the phase difference between the voltage and current of the AC power supply and the command value. Means for generating a command of the input voltage real axis component of the converter, and inputting the command of the input voltage imaginary axis component and the command of the input voltage real axis component, and applying the pulse width modulated power to the pulse width modulation power converter. Gate signal Means for generating a pulse width modulated power converter, wherein the current limiting means sets the predetermined value to the peak value when the peak value of the alternating current of the pulse width modulated power converter is equal to or more than a predetermined value. 2. A control device for a pulse width modulation power converter, comprising: means for narrowing down in response to the following.