CN1061486C - Wave-shape continuously changing method in power changing technology - Google Patents

Abstract

The present invention relates to a waveform continuous conversion method in power conversion technology, which can be applied to a high voltage power conversion system controlled in a closed-loop mode or an open-loop mode. Through the actual output frequency value of a calculation system and the final operation frequency value of a setting system respectively, by a voltage-frequency curve or a fuzzy algorithm, the peak value of output line voltage is obtained; then, according to the value range of the peak value of the line voltage, an algorithm for a main controller is regulated so that the triphase real-time output quantity is calculated. In the method, based on the premise that the line voltage is guaranteed to be sinusoidal, the shape of the output waveforms of phase voltage can be continuously regulated so that stepless change is realized, and the maximum voltage utilization rate, the optimum line voltage waveforms and the minimum harmonic waves of inversion units are guaranteed.

Description

Waveform continuous transformation method in the power converter technology

The present invention relates to a kind of power converter technology, relate to a kind of waveform continuous transformation method or rather.

In the power converter technical field, the effect of converter or inverter is that direct current is transformed to alternating current output, its concrete transform method has two kinds usually, and a kind of is common sine wave modulation method, and another kind is exactly voltage vector control method (a VVC method).In these two kinds of methods, the sine wave modulation method can realize that line voltage and phase voltage are sine, and in the voltage vector control method, its phase voltage is not that sine but line voltage are for sinusoidal, its advantage is that voltage utilization (ratio of the peak value of output line voltage and phase voltage) improves 15% than sine wave modulation method, can reach 2.

In above-mentioned two kinds of power converter technology, the voltage utilization right and wrong of its waveform transformation technology are successional, if the simple sine wave modulation method that adopts can only adopt pulse-width modulation when low-frequency and low-voltage, output harmonic wave is big, and is difficult to realize desired voltage when high frequency voltage; If simple adopt the VCC method, though the output variable problem can solve high frequency voltage the time, the more last method of output harmonic wave is more serious during low-frequency and low-voltage.The line voltage U _AB, U _BC, U _ACWith phase voltage U _A, U _B, U _CBetween become 3 the visible Fundamental Theory of Electrical Engineering teaching material of fixed relationship; Relevant voltage electricity transform method and converting means thereof can be referring to Chinese patent ZL 95 119585.9 " a kind of high-voltage power transform method and converting means thereof ".

Waveform continuous transformation technology is a kind of technology of continuous adjusting phase voltage output waveform, and retention wire voltage is output as sinusoidal wave constantly by the phase voltage output waveform is carried out corresponding deformation, thereby can guarantee optimum utilization rate of equipment and installations and waveform output true to nature.

The objective of the invention is to design the waveform continuous transformation method in a kind of power converter technology, realize voltage utilization adjusting continuously between 1.15-2, thereby guarantee optimum rate of utilization and the output of best line voltage waveform and the minimum harmonic wave of inversion unit from start to finish.

Method of the present invention can realize like this that the waveform continuous transformation method in a kind of power converter technology is applied in the closed-loop control system, it is characterized in that may further comprise the steps:

A. in the main control unit of equipment, preset the output variable set point of a controlled device, the actual output value of detection of dynamic controlled device in equipment operation, and collection is delivered to main control unit;

B. the actual output variable that will gather of main control unit is compared with the set point that presets, and determines the actual output frequency value F of power conversion system to calculate ω=2 π F again according to comparative result;

C. obtain the line voltage peak U of power conversion system output according to predefined voltage-frequency curve ₁

D. according to known every mutually in fixed middle dc voltage value U in maximum available superpositing unit number N and the power conversion system _dWith according to line voltage peak U ₁Span select the algorithm of main control unit, calculate real-time three-phase output voltage U _A(t), U _B(t), U _C(t);

E. according to the three-phase output voltage U that calculates _A(t), U _B(t), U _C(t) instantaneous value is with the middle dc voltage value U of power unit module _dCompare, the output state of determining corresponding each inversion unit of phase is plus or minus or zero.

Method of the present invention also can realize like this: the waveform continuous transformation method in the another kind of power converter technology, be applied in the open-loop control system, and it is characterized in that may further comprise the steps:

A. in the main control unit of equipment, a setpoint frequency value Fm is set, accelerates to Fm gradually after the power conversion system starting by man-machine interface;

B. according to the actual output frequency value F of system, and obtain the line voltage peak U of output according to predefined voltage-frequency curve ₁

C. according to known every mutually in fixed middle dc voltage value U in maximum available superpositing unit number N and the power conversion system _dWith according to line voltage peak U ₁Span select the algorithm of main control unit, calculate real-time three-phase output voltage U _A(t), U _B(t), U _C(t):

D. according to the three-phase output voltage U that calculates _A(t), U _B(t), U _C(t) instantaneous value is compared with the middle dc voltage value of power unit module, and the output state of determining corresponding each inversion unit of phase is plus or minus or zero.

Waveform continuous transformation method of the present invention, in the shape that guarantees to regulate continuously under the prerequisite of line voltage for sine the phase voltage output waveform, according to the amplitude requirement of output line voltage and the number of each maximum available unit module mutually, the shape of the output waveform of phase voltage becomes " fat " gradually from " thin ", its variation is grade control method that has of only getting several points in the stepless rather than common transform method, can realize voltage utilization adjusting continuously between 1.15-2, realized that each all has the power unit module of maximum number to participate in stack mutually from start to finish and utilizes existing equipment to realize big as far as possible line voltage output in whole line change in voltage scope, thereby guaranteed the optimum rate of utilization of inversion unit and the output and the minimum harmonic wave of best line voltage waveform.

Further specify method of the present invention below in conjunction with embodiment and accompanying drawing.

Fig. 1 is a kind of high voltage converter structural principle block diagram that adopts the power unit module superimposing technique.

Fig. 2 is the waveform transformation process schematic diagram that adopts waveform continuous transformation technology of the present invention.

Referring to Fig. 1, the alternating current-direct current power converting method that high voltage converter adopted shown in the figure is not traditional integral transformation method, but utilize the current potential principle of stacking, the electric power conversion method of AC and DC voltage in the middle of adopting, promptly no matter the complete machine input is alternating current or direct current, the current potential to each other that all it is transformed into certain way is interstage exchange independently, form respectively the intermediate dc of identical way again behind the rectifying and wave-filtering, by series resonant inverter electric bridge and stack according to certain rules, export required single-phase alternating current, three-phase alternating current or direct current at last.

The system's main circuit that adopts this alternating current-direct current power converting method is to adopt the unit module stack and regulate output voltage with the method that arbitrary module is wherein done pulse-width modulation among a small circle (PWM), compare with the method for simple employing PWM, this method can make harmonic components greatly reduce, its reason is exactly because adopted the mode of heap ripple, the module that participates in the stack of heap ripple is many more, and the waveform of its output is also true to nature more.Because the output of high voltage converter need guarantee certain voltage-frequency than (constant or adjustable, by the decision of loading moment change curve), thereby during low frequency output, its output voltage needs corresponding reduction.If adopt single modulator approach, the number of modules that must cause participating in stack when low frequency reduces, and then can only adopt the PWM method to come regulation voltage when low merely to a certain degree the time.So we wish to have unit module as much as possible to participate in the heap ripple, promptly adopt the voltage utilization low modulator approach of trying one's best when low-frequency and low-voltage; And for the consideration to system's output capacity, wish under the condition of existing equipment, to export the high voltage of trying one's best again, deal with input line voltage situation on the low side, thereby voltage utilization must be improved, the sine wave modulation mode that is higher than standard promptly will adopt the high modulation system of voltage utilization when high-frequency and high-voltage.Caused waveform continuous transformation method of the present invention by the consideration of above two aspects.

The main circuit of figure mesohigh frequency converter is by A, B, C three phase compositions, and each is formed by stacking by the identical M of a functional structure unit module, and each unit module is made up of rectification unit, filter unit and inversion unit (stack electric bridge).The control of complete machine mainly is responsible for by main control unit 1, and main control unit 1 is finished running state monitoring, calculation of parameter, the realization of control algolithm and the output of control signal of complete machine.Main control unit 1 is finished the calculating and the output of respectively exporting control signal according to the regulation of the inventive method to certain operation algorithm, controls the operating state of each unit module, thereby obtains corresponding output waveform at each phase output terminal.

Below in conjunction with the algorithm of introducing main control unit of the present invention referring to Fig. 2 in detail.

When the output line voltage amplitude require lower, its output line voltage peak value be 0≤U1≤ $\frac{2}{3}\sqrt{3}\·N\·U_d$ The time, the algorithm of adjustment main control unit makes the output phase voltage of A, B, C three-phase satisfy following rule:

Thereby guaranteed that three-phase top-stitching voltage is:

In the formula related N be every mutually in maximum available superpositing unit number, ω=2 π F, F is the actual output frequency value of system, U _dActual output voltage value when detecting for system dynamics.Its output waveform as among Fig. 2 1. shown in.When the output line voltage peak value is

Adjust the algorithm of main control unit, make the output phase voltage of A, B, C three-phase satisfy following rule:

And corresponding line voltage is:

Related T in the formula ₁, U _sBe intermediate variable, its output waveform as among Fig. 2 2. shown in.In this constant interval, each all guarantees to have maximum N available unit module to participate in the voltage stack mutually, has guaranteed perfect waveform output.In above-mentioned (2) formula, when ${\mathrm{<figure-callout\; id="1"\; label="U"\; filenames="9811719700141.png"\; state="\{\{state\}\}">U</figure-callout>}}_1=\sqrt{3}\&CenterDot;N\&CenterDot;U_d$

At this moment, three-phase phase voltage and three-phase top-stitching voltage are respectively:

This moment this working point be exactly the said common sine wave modulation method of preamble, as among Fig. 2 3. shown in, be a point in the inventive method continuous transformation process.When the output line voltage amplitude have relatively high expectations into $\sqrt{3\&CenterDot;}N\&CenterDot;U_d\&le;{\mathrm{<figure-callout\; id="1"\; label="U"\; filenames="9811719700141.png"\; state="\{\{state\}\}">U</figure-callout>}}_1\&le;2N\&CenterDot;U_d$ The time, the algorithm of adjustment main control unit makes the output phase voltage of A, B, C three-phase satisfy following rule:

Related T in the formula ₂, U _sBe intermediate variable, satisfy: T ₂With N, U _d, U ₁Between relation satisfy:

Thereby guaranteed that three-phase top-stitching voltage is:

Its output waveform as among Fig. 2 4. shown in.In this constant interval, each all guarantees to have maximum N available unit module to participate in the current potential stack mutually, thereby has guaranteed the output of perfect waveform output and big as far as possible line voltage.In above-mentioned (4) formula, work as U ₁=2NU _d

The time, at this moment, three-phase phase voltage and three-phase top-stitching voltage are respectively:

This moment this working point be exactly the modulator approach of the said VVC of preamble, as among Fig. 2 5. shown in, be another point in the inventive method continuous transformation process.

3. or variation 5. Fig. 2 draws out the continuous change procedure of waveform that adopts the inventive method visually, and to 5. continuous modification, and traditional level method is arranged is to phase voltage waveform, is the transform method of only getting two specified points in the transform method of the present invention from 1..

For example, if establishing the main circuit unit module dc voltage of HVF high voltage converter is Ud=540V, its every mutually maximum available unit module is counted N=8, then 8 exportable maximum voltages of stack are 4320V (peak value), adopt method of the present invention (WCC), voltage utilization is regulated between 1.15-2 continuously, when line voltage (peak value) output is between 4970V-8640V, can guarantee that all every part has 8 modules to participate in the heap ripple, corresponding voltage effective value is 3510V-6100V.

If system adopts permanent torque voltage-frequency curve, no torque magnification, rated frequency is 50Hz, when rated voltage is 6000V (line voltage effective value), when 0-29.2Hz (being 0V to 3510V), adopt method 1., adopt method 2. to begin continuous adjusting afterwards, when 44Hz, carry out the transition to method 3., from 44Hz-50Hz, adopt method 4. to regulate continuously, when 50.8Hz, carry out the transition to method 5..There is 1 module to participate in the heap ripple at 0-3.6Hz, there are 2 modules to participate in the heap ripple at 3.7-7.3Hz, there are 3 modules to participate in the heap ripple at 7.4-10.9Hz, there are 4 modules to participate in the heap ripple at 11-14.6Hz, there are 5 modules to participate in the heap ripple at 14.7-18.2Hz, have 6 modules to participate in the heap ripple, have 7 modules to participate in the heap ripple at 22-25.5Hz at 18.3-21.9Hz, there are 8 modules to participate in the heap ripple from 25.6Hz always, thereby guaranteed waveform output true to nature.

According to above-mentioned same condition, if the simple number of modules that adopts 3. method (common sine wave modulation method) then to participate in stack when same frequency can reduce, simultaneously, can't output rated voltage (6000V); If the simple method (method of VVC) that adopts 5., though can realize rated voltage output, the number of modules that participates in stack when same frequency can more reduce.Tabulation illustrates three kinds of modulator approaches and participates in laminating module number and pairing output frequency thereof below.

Participate in the laminating module number	Pairing reference frequency output
				The method of WCC	The simple method that adopts 3.	The simple method that adopts 5.
	1	0Hz-3.6Hz	0Hz-5.5Hz				0Hz-6.4Hz
2				3.7Hz-7.3Hz	5.6Hz-11.0Hz	6.5Hz-12.7HZ
	3	7.4Hz-10.9Hz	11.1Hz-16.5Hz				12.8Hz-19.1Hz
4				11Hz-14.6Hz	16.6Hz-22.0Hz	19.2Hz-25.5Hz
	5	14.7Hz-18.2Hz	22.1Hz-27.6Hz				25.6Hz-31.8Hz
6				18.3Hz-21.9Hz	27.7Hz-33.0Hz	31.9Hz-38.2Hz
	7	22Hz-25.5Hz	33.1Hz-38.6Hz				38.3Hz-44.6Hz
8				25.6Hz-50.8Hz	38.7Hz-44.1Hz	44.7Hz-50.8Hz

The application of the inventive method, make us to adjust voltage utilization continuously and become possibility according to the size variation of output line voltage, so just can guarantee in the process of system heap ripple work, can keep the unit module of maximum number to participate in the heap ripple always, thereby the reliability of utilization rate of equipment and installations and device is greatly improved, make the current harmonics of system's output drop to minimum value.The application of this method is also sinusoidal for realizing essence, realizes zero harmonic wave output, and harmonic carcellation is to electrical network, opened up new approach to the influence of load.

Claims (3)

1. the waveform continuous transformation method in the power converter technology is applied in the closed-loop control system, it is characterized in that may further comprise the steps:

A. in the main control unit of equipment, preset the output variable set point of a controlled device, the actual output value of detection of dynamic controlled device in equipment operation, and collection is delivered to main control unit;

B. the actual output value that will gather of main control unit is compared with the setting value that presets, and determines the actual output frequency value F of system to calculate ω=2 π F again according to comparative result;

C. obtain the line voltage peak U of output according to predefined voltage-frequency curve ₁

D. according to known every mutually in fixed middle dc voltage value U in maximum available superpositing unit number N and the power conversion system _dWith according to line voltage peak U ₁Span select the algorithm of main control unit, calculate real-time three-phase output voltage U _A(t), U _B(t), U _C(t);

E. according to the three-phase output voltage U that calculates _A(t), U _B(t), U _c(t) instantaneous value is with the middle dc voltage value U of power unit module _dCompare, the output state of determining corresponding each inversion unit of phase is plus or minus or zero.

2. the waveform continuous transformation method in the power converter technology is applied in the open-loop control system, it is characterized in that may further comprise the steps:

A. in the main control unit of equipment, a setpoint frequency value Fm is set, accelerates to Fm gradually after the power conversion system starting by man-machine interface;

B. according to the actual output frequency value F of system, and obtain the line voltage peak U of output according to predefined voltage-frequency curve ₁

C. according to known every mutually in fixed middle dc voltage value U in maximum available superpositing unit number N and the power conversion system _dWith according to line voltage peak U ₁Span select the algorithm of main control unit, calculate real-time three-phase output voltage U _A(t), U _B(t), U _C(t);

D. according to the three-phase output voltage U that calculates _A(t), U _B(t), U _C(t) instantaneous value is compared with the middle dc voltage value of power unit module, and the output state of determining corresponding each inversion unit of phase is plus or minus or zero.

3. the waveform continuous transformation method in the power converter technology according to claim 1 and 2 is characterized in that: the span of described line voltage peak U1 and corresponding calculating three-phase output phase voltage U _A(t), U _B(t), U _C(t) algorithm comprises: a. works as U ₁Be less than or equal to more than or equal to zero $\frac{2}{3}\sqrt{3}\&CenterDot;N\&CenterDot;U_d$ The time, the algorithm of A, B, C three-phase output phase voltage is adjusted into:

B. work as U ₁More than or equal to $\frac{2}{3}\sqrt{3}\&CenterDot;N\&CenterDot;U_d$ Be less than or equal to $\sqrt{3}\&CenterDot;N\&CenterDot;U_d$ , and make intermediate variable $U_s=U_1/2\sin (\frac{\mathrm{\&pi;}}{6}+T_1)$ , intermediate variable T ₁With every mutually in maximum available superpositing unit number N and U ₁, U _dBetween satisfy $N\&CenterDot;U_d=U_1\sin (\frac{\mathrm{\&pi;}}{3}+T_1)/2\sin \left(\frac{\mathrm{\&pi;}}{6}{+T}_1\right)$ The time, the algorithm of A, B, C three-phase output phase voltage is adjusted into:

C. work as U ₁Equal $\sqrt{3}\&CenterDot;N\&CenterDot;U_d$ The time, the algorithm of A, B, C three-phase output phase voltage is adjusted into: D. work as U ₁Greater than $\sqrt{3}\&CenterDot;N\&CenterDot;U_d$ Be less than or equal to 2.N.U _d, and make intermediate variable U _s, T ₂With U _d, U ₁And satisfy between N $U_s=U_1/2\&CenterDot;\&lsqb;\sin (\frac{\mathrm{\&pi;}}{3}+T_2)-\sin T_2\&rsqb;$

The time, the algorithm of A, B, C three-phase output phase voltage is: $u_B\left(t\right)=u_A\left(t\right)\&CenterDot;e^{-j\frac{2\mathrm{\&pi;}}{3}}$ E. work as U ₁=2NU _dThe time, the algorithm of A, B, C three-phase output phase voltage is adjusted into:

$u_B\left(t\right)=u_A\left(t\right)\&CenterDot;e^{-j\frac{2\mathrm{\&pi;}}{3}}$ $u_C\left(t\right)=u_A\left(t\right)\&CenterDot;e^{-j\frac{4\mathrm{\&pi;}}{3}}.$

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