CN101807877B - Control method for matrix frequency converter during supply of DC source - Google Patents

Abstract

The invention discloses a control method for a matrix frequency converter during supply of a DC source. Under the condition of the supply of the DC source, a positive pole and a negative pole of the DC source are respectively connected to three input ends of the matrix frequency converter correspondingly, namely an R input end, an S input end and a T input end; and the matrix frequency converter converts DC into AC to drive a motor to work. The control method can control the motor to normally work by adopting the DC source under the condition that a three-phase AC source is powered off.

Description

The control method of matrix frequency converter when DC power supply

Technical field

The present invention relates to the control method of a kind of matrix frequency converter when DC power supply.

Background technology

As shown in Figure 2, traditional frequency converter generally adopts the structure of handing over orthogonal.Rectifier bridge heap 1 AC rectification with three-phase alternating-current supply becomes direct current to give big electric capacity 3 chargings, and inversion assembly 4 is transformed into alternating current to direct current, CD-ROM drive motor 5 runnings.When three-phase alternating-current supply had a power failure, frequency converter can be directly connected to the positive and negative electrode of storage battery 2 (DC power supply) on the big electric capacity 3 of major loop, gave 4 power supplies of inversion assembly with CD-ROM drive motor 5 runnings.For inversion assembly 4, rectifier bridge heap 1 does not have essential distinction with the direct current that storage battery 2 provides, and inversion assembly 4 can both 5 runnings of driven motor.

Referring to Fig. 1, matrix frequency converter is the structure of friendship-friendship Direct Conversion.Typical matrix frequency converter generally adopts the three-phase input three-phase way of output, and input terminal connects the three-phase alternating-current supply (R, S, T) of electric power system, and lead-out terminal connects three phase windings (U, V, W) of motor.Controller 7 detects supply voltages through incoming line 9, and after carrying out matrixing and calculating, output trigger impulse 8 power controlling assemblies 6 are directly converted to 5 runnings of alternating current CD-ROM drive motor with the alternating current of three-phase alternating-current supply.

Because characteristics such as matrix frequency converter has that input power factor can be regulated arbitrarily, but power two-way flow, output voltage and frequency adjustable and compact conformation, volume are little, efficient height make it become a focus that drags the control field gradually.In many applications, have a power failure at three-phase alternating-current supply, and can only provide under the situation of DC power supply (generally supplying direct current) to matrix frequency converter with storage battery, also need the matrix frequency converter can also the driven motor running.But not having big electric capacity on the major loop of matrix frequency converter, when three-phase alternating-current supply has a power failure, is the connected mode that can not directly adopt the traditional frequency conversion device if DC power supply is connected on the matrix frequency converter.

Summary of the invention

The technical problem that the present invention will solve provides the control method of a kind of matrix frequency converter when DC power supply, can under the situation that three-phase alternating-current supply has a power failure, adopt the normal operation of DC power supply control motor.

For solving the problems of the technologies described above; The control method of matrix frequency converter of the present invention when direct current supply is; Under the situation of DC power supply, with positive pole and corresponding respectively three inputs that are connected to matrix frequency converter of negative pole, i.e. R input, S input and the T input of DC power supply; Matrix frequency converter is transformed into alternating current with direct current, the CD-ROM drive motor running.

Adopt method of the present invention; Mode when matrix frequency converter fully can be according to normal three-phase alternating-current supply power voltage supply is carried out VFC; The alternating current CD-ROM drive motor of output variable-frequency variable-voltage turns round, and satisfies the needs of use DC power supply control motor under the three-phase alternating-current supply power-off condition.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention is done further detailed explanation:

Fig. 1 is the structure chart that matrix frequency converter adopts control method of the present invention;

Fig. 2 is existing traditional frequency conversion device structure chart;

Fig. 3 is the oscillogram of three-phase alternating-current supply voltage.

Embodiment

The control strategy of matrix frequency converter has multiple; Like Venturini control method, means of space vector representation, scalar modulation method etc., but their control purpose is identical, and promptly the voltage of output needs frequency and adjustable amplitude value; Input power factor is approaching ± and 1, and input current waveform is sinusoidal.In order to achieve the above object, matrix frequency converter needs to measure in real time the three-phase alternating-current supply voltage of input, input voltage is carried out matrixing, with control output voltage and input current.

The phase voltage of three-phase alternating-current supply is set at:

U _R(t)＝U _mcosθ

$U_S\left(t\right)=U_m\cos (\mathrm{\θ}-\frac{2\mathrm{\π}}{3})$

$U_T\left(t\right)=U_m\cos (\mathrm{\θ}+\frac{2\mathrm{\π}}{3})$

The line voltage of three-phase alternating-current supply is set at:

U _RS(t)＝U _R(t)-U _S(t)

U _ST(t)＝U _S(t)-U _T(t)

U _TR(t)＝U _T(t)-U _R(t)

θ=2 π ft wherein, the frequency of f supply voltage, U _mIt is the amplitude of phase voltage

The three-phase alternating-current supply voltage waveform is as shown in Figure 3, and six corresponding line voltage and angle θ values of state point are listed in the following table 1 among the figure, and wherein k is an integer.

Table 1

When three-phase alternating-current supply had a power failure, the mode that DC power supply is connected to the matrix frequency converter input had 6 kinds.For under the situation of direct current supply; Matrix frequency converter is still pressed the mode variable-frequency variable-voltage of matrix; Three inputs (R, S, T) of matrix frequency converter all must be connected on the positive and negative electrode of DC power supply, but three inputs can not be connected on the same electrode of DC power supply simultaneously.The mode of connection is as shown in table 2.Wherein V is the direct voltage amplitude that DC power supply provides.

Table 2

Comparison through table 1 and table 2 can find out, it is closely similar that DC power supply is connected to six state points of three-phase alternating-current supply voltage waveform among the corresponding state of six kinds of modes of matrix frequency converter input and Fig. 3, and unique difference is the amplitude difference of voltage.During the three-phase alternating-current supply power supply, six corresponding line absolute value of voltage of state point have two kinds of 1.5U _mWith 0, U _mAmplitude size by the three-phase alternating-current supply phase voltage is confirmed.Under the situation of dc power supply, six corresponding line absolute value of voltage of state point have two kinds of V and 0, and V is the direct voltage amplitude.Provide galvanic device different, the size of V maybe be different.

In conjunction with shown in Figure 1, under the normal situation of three-phase alternating-current supply voltage, matrix frequency converter can measure the amplitude U of three-phase alternating-current supply voltage in real time through incoming line 9 _mWith angle θ, according to the requirement of control motor 5 runnings the three-phase alternating-current supply input voltage is carried out matrixing, the alternating current of output variable-frequency variable-voltage.Wherein the angle θ of three-phase alternating-current supply voltage is a real-time change, and frequency is power frequency f.

Under the situation of DC power supply; Controller 7 with reference to table 2, can be judged the mode that DC power supply is connected to three input terminals of matrix frequency converter through the detection of incoming line 9; Obtain corresponding state point and angle θ value, also can measure the dc voltage value V of DC power supply simultaneously.For example: when the line voltage U that measures _RS(t)=and V, U _ST(t)=0, U _TR(t)=-during V, just can judge DC power supply be connected to the matrix frequency converter input terminal the corresponding three-phase alternating-current supply of mode state point 1..At this moment, the positive pole of DC power supply is connected on the input terminal R of matrix frequency converter, and the negative pole of DC power supply is connected on the input terminal S and T of matrix frequency converter, and angle θ value equals 0 degree.Mode when the controller 7 of matrix frequency converter fully can be according to normal power source (being three-phase alternating-current supply) power voltage supply is carried out VFC, and the alternating current of output variable-frequency variable-voltage goes CD-ROM drive motor 5 runnings.Unique difference is that angle θ is indeclinable, and the supply voltage amplitude is V.

Claims (2)

1. the control method of a matrix frequency converter when DC power supply; It is characterized in that: under the situation of DC power supply; Positive pole and corresponding respectively three inputs that are connected to matrix frequency converter of negative pole with DC power supply; Be R input, S input and T input, matrix frequency converter is transformed into alternating current with direct current, the CD-ROM drive motor running;

The positive pole of said DC power supply and negative pole are connected to R input, S input and the T input of matrix frequency converter by one of following six kinds of modes;

First kind, the said anodal R input that connects, negative pole connects S input and T input;

Second kind, said anodal R input and the S input of connecting, negative pole connects the T input;

The third, the said anodal S input that connects, negative pole connects R input and T input;

The 4th kind, said anodal S input and the T input of connecting, negative pole connects the R input;

The 5th kind, the said anodal T input that connects, negative pole connects R input and S input;

The 6th kind, said anodal R input and the T input of connecting, negative pole connects the S input;

Said six kinds of connected modes are six state points of corresponding three-phase alternating-current supply voltage respectively, and matrix frequency converter carries out matrixing, output AC by six state points corresponding angle and actual voltage value to DC power supply.

2. control method as claimed in claim 1 is characterized in that:

The state point 1 of first kind of corresponding three-phase alternating-current supply voltage of connected mode, the three-phase ac power cord voltage of this state point 1 and corresponding angle are:

U _RS(t)＝-U _TR(t)＝1.5U _m，U _ST(t)＝0，θ＝2πk+0；

The state point 2 of second kind of corresponding three-phase alternating-current supply voltage of connected mode, the three-phase ac power cord voltage of this state point 2 and corresponding angle are:

U _ST(t)＝-U _TR(t)＝1.5U _m，U _RS(t)＝0， $\mathrm{\θ}=2\mathrm{\πk}+\frac{\mathrm{\π}}{3};$

The state point 3 of the corresponding three-phase alternating-current supply voltage of the third connected mode, the three-phase ac power cord voltage of this state point 3 and corresponding angle are:

U _ST(t)＝-U _RS(t)＝1.5U _m，U _TR(t)＝0， $\mathrm{\θ}=2\mathrm{\πk}+\frac{2\mathrm{\π}}{3};$

The state point 4 of the 4th kind of corresponding three-phase alternating-current supply voltage of connected mode, the three-phase ac power cord voltage of this state point 4 and corresponding angle are:

U _TR(t)＝-U _RS(t)＝1.5U _m，U _ST(t)＝0，θ＝2πk+π；

The state point 5 of the 5th kind of corresponding three-phase alternating-current supply voltage of connected mode, the three-phase ac power cord voltage of this state point 5 and corresponding angle are:

U _TR(t)＝-U _ST(t)＝1.5U _m，U _RS(t)＝0， $\mathrm{\θ}=2\mathrm{\πk}+\frac{4\mathrm{\π}}{3};$

The state point 6 of the 6th kind of corresponding three-phase alternating-current supply voltage of connected mode, the three-phase ac power cord voltage of this state point 6 and corresponding angle are:

U _RS(t)＝-U _ST(t)＝1.5U _m，U _TR(t)＝0， $\mathrm{\θ}=2\mathrm{\πk}+\frac{5\mathrm{\π}}{3};$

U wherein _mBe the amplitude of three-phase alternating-current supply phase voltage, k is an integer.

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