JPH07274518A - Pwm converter control device - Google Patents

Abstract

PURPOSE:To control an input current waveform even in the case of saturating a DC voltage control amplifier. CONSTITUTION:A PWM reference waveform synthesizing part 31 is provided in a cable way between an instantaneous comparator amplifier 17 and a matching device 20. The reference synthesizing part 31 is constituted of an adder 32, amplifier 33 supplied with an output of this adder 32, switches 34, 35 and a NOT circuit 36. An output of the instantaneous comparator amplifier 17 is supplied to one end of the adder 32, and an output of a correction sinusoidal wave detecting part 37 for obtaining a start time correction sinusoidal wave signal Vsa from an input voltage detection signal Vin is supplied to the other end. A detecting part 38 is a fixed limiter use sinusoidal wave detecting part at saturation time of a V amplifier, and a sinusoidal wave signal Vsb detected in this detecting part 38 is supplied to the matching device 20 through the switch 35. A comparator 39 is a V amplifier saturation hysteresis comparator, and in this comparator 39, an output of an amplifier 14 is compared, to supply an output of the comparator to the switch 35 and NOT circuit 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PWM converter control device for controlling an input current waveform of a PWM converter in UPS, CVCF, etc. without being influenced by distortion of an input voltage waveform.

[0002]

2. Description of the Related Art Conventionally, a PWM converter has been used as a forward conversion unit used in a CVCF device. PW
As a method of controlling the M converter, voltage control is performed so that the DC voltage output from the PWM converter is constant, and the input current of the PWM converter also becomes a sine wave that matches the input voltage phase ( The power factor is 1). The control circuit of this PWM converter is shown in FIG. Reference numeral 10 is a P in which a semiconductor element is connected to a full bridge circuit.
In the main circuit of the WM converter, the input side is connected to the power supply Es via the LC filter F, and the output side is the DC capacitor C1.
Are connected.

[0003] 11 in the control unit of the PWM converter consisting of 12 to 22, the DC voltage command V _DC by the output voltage detector and the detected DC voltage signal V _DC from (not shown) the DC voltage command setting unit 22 of the PWM converter 10 set and the soft start signal Vss (Vss = 0 in a steady state) from the soft start circuit 12 which starts with the start signal are compared by the matching device 13, amplified by the DC voltage control PI amplifier 14, and the amplified signal. Then, the input voltage detection signal Vin detected by the voltage detector PT1 is multiplied by the multiplier 15 to generate a reference sine wave Vs1 at the output. The PI amplifier 14 starts its operation in response to a start command START.

An input current detector C is applied to the reference sine wave Vs1.
The input current detection signal Iin detected at T1 is matched by the matching device 16, the error is amplified by the input current waveform control instantaneous comparison amplifier 17, and the amplified signal is matched by the matching device 20 from the triangular wave generator 18. Then, the error is compared with the comparator 19 to generate a PWM gate signal, the signal is input to the AND circuit 21, and the PWM gate signal is transmitted by the start command START. This gate signal is given to the semiconductor element of the PWM converter 10 to control the PWM converter 10. Therefore, the input current I of the PWM converter is controlled by following the waveform of the input voltage Vs.

[0005]

In the above-mentioned conventional PWM converter, the input current is detected so that the input current becomes a sine wave, and is instantaneously compared with the reference sine wave Vs1. However, since the loop gain is high in the input current waveform control of the PWM converter, the control system is easily saturated. Therefore, particularly at the time of starting or when the DC voltage is low, there is a problem that the PWM reference waveform Vs2 that is the output of the amplifier 17 is saturated and does not become a sine wave and the input current control cannot be performed.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a PWM converter control device capable of controlling an input current waveform even when an amplifier system is saturated.

[0007]

In order to achieve the above object, the present invention provides a PWM converter for controlling an input current by following a reference voltage waveform, and a PWM converter for the PWM converter. A PWM converter control device having a DC output voltage detection signal, an input voltage detection signal and an input current detection signal, and a PWM converter control unit for obtaining a gate signal of the PWM converter at an output, The control unit includes a DC voltage control amplifier for amplifying a DC output voltage detection signal, a multiplier into which an output signal of the amplifier and an input voltage detection signal are introduced, and a reference sine wave signal is output, and an output of the multiplier. The input current waveform control instantaneous comparison amplifier that amplifies the error signal between the reference sine wave signal and the input current detection signal obtained in step 1, and the output signal of this instantaneous comparison amplifier and the input voltage detection signal The time-correction sine wave signal is supplied, and a PWM waveform is generated from a reference waveform signal synthesizing section for synthesizing these signals to obtain a PWM reference waveform signal at the output, and the output signal of this synthesizing section and the carrier signal from the triangular wave generator. P that creates a signal
And a WM gate signal generator.

According to a second aspect of the present invention, when the DC voltage control amplifier is saturated, the signal switching unit provided in the reference waveform signal synthesizing unit is switched by the output signal of the DC voltage control amplifier to fix the starting correction sine wave signal at saturation. The limiter sine wave signal is supplied to the reference waveform signal synthesizer.

[0009]

When the input current is controlled by the PWM converter, when the DC voltage is low and the DC voltage control amplifier is saturated, at start-up, when the DC voltage control system is not operating,
The bias component of the startup corrected sine wave signal is added to the reference waveform signal so that the input current can be controlled.

Further, when the DC voltage control amplifier is saturated, the reference waveform signal becomes maximum. Therefore, the reference waveform signal is switched to a fixed limiter sine wave signal, and the input current control is performed so that the reference waveform signal becomes a sine wave. It can be so.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 1, and the same portions as those in FIG. 2 are designated by the same reference numerals. In FIG. 1, a PWM reference waveform synthesizer 31 is provided in the electric path between the instantaneous comparison amplifier 17 and the matching device 20. The reference synthesizing unit 31 includes an adder 32, an amplifier 33 to which the output of the adder 32 is supplied, switches 34 and 35, and a NOT circuit 36.

The output of the instantaneous comparison amplifier 17 is supplied to one end of the adder 32, and the input voltage detection signal Vi is supplied to the other end.
The output of the correction sine wave detection unit 37 that obtains the startup correction sine wave signal Vsa is supplied from n. Reference numeral 38 denotes a fixed limiter sine wave detection unit when the V amplifier is saturated, and the sine wave signal Vsb detected by the detection unit 38 is supplied to the matching device 20 via the switch 35. 39 is a V amplifier saturation hysteresis comparator, and this comparator 39 is a PI amplifier 1
4 is compared and the output is compared with the switch 35 and NO.
It is supplied to the T circuit 36.

When the input current is controlled by the PWM converter 10, when the direct current voltage is low and the PI amplifier 14 is saturated, the input current waveform can be controlled at the time of starting and when the direct current voltage control system is not operating. To do so, do the following: As shown in FIG. 1, when starting, the PI amplifier 1
When 4 is "0", PW is generated by the input current detection signal Iin.
In order to prevent the M reference waveform Vs2 from becoming "0", that is, the saturation of the amplifier, the start-up correction sine wave signal Vs
The bias component of a is added to the adder 3 of the PWM reference waveform synthesizer 31.
Supply to 2 and add this.

Further, when the PI amplifier 14 is saturated, the output of the PWM reference waveform synthesizer 31 becomes maximum (due to the saturation of the instantaneous comparison amplifier 17), so that the output waveform becomes a square, and therefore the sine wave signal Vsb By switching to, the PWM reference waveform Vs2 becomes a sine wave signal. This allows the input current waveform control. Note that the above switching is not saturation of the PI amplifier 14,
It is also possible to compare the levels when the DC voltage is detected.

[0015]

As described above, the present invention has the following effects. When the DC voltage is controlled by the PWM converter and the input current waveform is controlled, the input current waveform can be controlled even if the DC voltage control amplifier system is saturated.

[Brief description of drawings]

FIG. 1 is a structural explanatory diagram of a UPS according to an embodiment of the present invention.

FIG. 2 is a block circuit diagram showing a converter according to a conventional example.

[Explanation of symbols]

 10 ... PWM converter 11 ... Converter control unit 14 ... DC voltage control PI amplifier 15 ... Multiplier 17 ... Instantaneous comparison amplifier 31 ... PWM reference waveform synthesis unit 37 ... Corrected sine wave detection unit 38 ... Fixed limiter sine wave detection unit 39 ... Hysteresis Comparator

Claims (2)

[Claims] 1. A PWM converter for controlling an input current by following a reference voltage waveform, and a DC output voltage detection signal, an input voltage detection signal and an input current detection signal of this PWM converter are input and output. In a PWM converter control device having a PWM converter control section for obtaining a gate signal of a PWM converter, the control section comprises a DC voltage control amplifier for amplifying a DC output voltage detection signal, and this amplifier. Output signal and input voltage detection signal are introduced to obtain a reference sine wave signal at the output, and an input current that amplifies the error signal between the reference sine wave signal and the input current detection signal obtained at the output of this multiplier. A waveform control instantaneous comparison amplifier and a start-up correction sine wave signal obtained from the output signal of this instantaneous comparison amplifier and the input voltage detection signal are supplied, and these signals are combined to output a PWM signal. It is characterized by comprising a reference waveform signal synthesizing unit for obtaining a quasi-waveform signal, and a PWM gate signal generating unit for producing a PWM gate signal from the output signal of this synthesizing unit and the carrier wave signal from the triangular wave generator. PWM converter control device. 2. When the DC voltage control amplifier is saturated,
The signal switch provided in the reference waveform signal synthesizing unit is switched by the output signal of the DC voltage control amplifier to supply the sine wave signal for fixed limiter at saturation from the correction sine wave signal at starting to the reference waveform signal synthesizing unit. The PW according to claim 1.
M converter control device.