DD288942A5 - METHOD FOR CONTROLLING ONE OR MULTI-PHASE CURRENT - Google Patents

Abstract

The invention relates to a method for controlling single-phase or multi-phase power converters. The method is applicable to the control of the valves in single-phase or multi-phase positively switched power converters, in particular four-quadrant actuators, according to the undershoot method. According to the invention, sinusoidal reference signals are compared with section-wise sinusoidal modulation signals. It reduces the overshoot content and the possibility of false pulses. Fig. 2 {method; control; Power converter, single-phase, multi-phase, forcibly extinguished; Four-quadrant; Reference signal; Modulation signal, sinusoidal, sections}

Description

Üsin ()) t- (2k-1) n / p) and its falling edge (M ") through the shape

~ Üsin (g) t (2k-1) n / p)

are characterized, where k represents the current pulse number.

2. The method according to claim 1, characterized in that a first (K 1) or second (K2) logic comparator signal is switched to the high state, when the falling edge of the modulation signal (M ") equal to the positive (R ⁺ ) or negative (R ^- ) reference signal and the same comparator signals (K 1, K2) are switched to the low state when the positive edge of the modulation signal (M ⁺ ) equal to the positive (R ⁺ ) and negative reference signal (R "). ) and from this the two drive pulses (A 1) and (A2) of the respectively complementary valve pairs (V 1, V 4 and V 2; V 3) are derived in such a way that with different polarity of the comparator signals (K 1, K 2) and high State of the first or second comparator signal (K 1, K 2) the respectively complementary valve pair A (V 1, V4 and V2, V3) are ignited.

3. The method according to claim 1 and 2, characterized in that the reference signals (R ⁺ ; R ^- ) are obtained by transformation of a complex voltage vector from a coordinate system rotating at a difference frequency.

4. The method according to claim 1 to 3, characterized in that in multi-phase converters each phase reference signal (R ⁺ ; R ") is assigned a synchronous modulation signal (M ⁺ ; M ^- ) of positive and negative polarity.

For this 1 page drawings

Field of application of the invention

The present method is suitable for driving single-phase or multi-phase forcibly extinguished power electronic actuators. Its application is particularly advantageous in mains converters (Vierquadrantonstellern) in traction or in pulse inverters for general three-phase drive technology.

Characteristics of the known state of the art

From BBC News 51, 1964; H.8 / 9 pp. 555-577 discloses the undershoot method for pulse-width-modulated drive control of inverters in which quasi-continuous generation and comparison of reference and modulation signals is performed by using analog circuits. The use of this method is bound to a very fast signal processing and in this form applicable only for three-phase systems. For systems with digital signal processing, a precise analytical determination of the intersections of reference and modulation signals on the basis of sine and delta voltage is not achievable. In DE-OS 3233337 (H 02 P13 / 18), therefore, a digital control unit for pulse inverters is proposed in which it is possible by sampling the sinusoidal reference signal to arrive for the respective sampling interval to an analytical pulse width calculation and subsequent systematic pulse output. The overshoot spectrum experiences thereby a slight deterioration. The method also leads to the generation of false pulses at the zero crossing of the reference signal. In particular, in the case of transmission to single-phase systems operating at twice the sampling frequency with respect to the pulse frequency, it leads to undesired transient operations in the mains current.

It has also been proposed in DE-OS No. 3,403,802 to use as the modulation signal instead of a delta voltage a sine voltage whose frequency is η times higher than that of the reference voltage and which is synchronized therewith. The disadvantage is that in the upper control range by the sinusoidal flattening of the modulating signal, the pulse width is no longer linearly controllable and limit effects arise.

2Ior the invention

The invention is intended to improve the state of the art in terms of actuator properties in stationary and dynamic operation, so as to achieve a higher utilization of the components and improved efficiency and to reduce the expense of signal processing.

Explanation of the essence of the invention

The invention has for its object to provide a general driving method for a single or multi-phase converter rectifiers with a quaslkontlnulerlichen sampling of the reference signal.

According to the invention, the output is achieved in that biw to form the ignition pulses after Unterschwingungsverfahren. multiphase sinusoidal reference signals of the general harmonic form

G ₀ COSCOt - GßSincüt

are compared with respective positive and negative signs with section-wise sinusoidal modulation signals, one of the pulse number ρ and the reference signal amplitude Ür dependent amplitude of size Ü _R / 8ln (n / p), the same angular frequency, a rising edge of the form

Üs! N {<ot- (2k-1) ii / p) and a falling edge of the form -Üslnlcut- {2k-DnVp)

k, herein represents the current pulse number, ρ the number of pulses per perlode.

A first or second comparator signal goes high when the falling edge of the modulation signal equals

is the positive or negative reference signal or in the low state, when the positive edge of the modulation signal is equal to the positive or negative reference signal. The drive pulses of the two complementary pairs of valves are derived in such a way that at different Komparatorslgnalen depending on the high state of the first and second

Komparatorslgnals the valves of the first and the second valve pair (for the opposite current direction) ignited

become.

The reference signals can be obtained by transforming a complex voltage vector from one with a difference frequency

be obtained rotating coordinate system.

For multi-phase applications, it is expedient for each phase refocusing signal to be a synchronously running modulation signal

assign with positive and negative polarity.

embodiment

The proposed method will be explained in more detail below with reference to an exemplary embodiment. In the drawings show

Fig. 1: a single-phase actuator and Fig. 2: the modulation and Zuendenignalbildung.

It is considered the pulse modulation of a single-phase variable, as z. As in power converters that are equipped with Vierquadrantenstellem, can be used. 1 shows such a four-quadrant controller which generates the alternating voltage U _w from a DC voltage Ud, for example the intermediate circuit voltage of an inverter, with the aid of the valves V1 to V4.

Fig. 2 shows the modulation and the formation of the Zuendenignale for the valves V1 to V4. The reference signals have the general harmonic form

with positive and negative signs respectively.

As modulation signals sinusoidal sections of the same fundamental frequency are used, the rising edge through

M ⁺ = Üsin (wt- (2K-1) n / p) and its falling edge by

M "= -Üsin (cot - (2k - 1) n / p)

k is the current pulse number, which in this example is always even for the rising edges and always odd for the falling edges, ρ is the number of pulses over the entire period.

The amplitude U of the modulation signal M ⁺ , M "is dependent on the possible peak value of the reference signal U _R and in relation to the level of the intermediate circuit voltage and is dependent on the number of pulses ρ per fundamental oscillation period

Ü = Ü "/ sin (n / p).

The control of the complementary valves V1 and V4 or V 2 and V 3 takes place, starting at equality of falling edge of the modulation signal M ~ with the positive or negative Reforenzsignal R ⁺ , R "or rising edge of the modulation signal M ⁺ with the negative or positive reference signal R ", R ⁺ and ending at equality of the falling edge of the modulation signal M * with the negative or positive reference signal R" ¹ , R ⁺ 'or rising edge of the ModulJtlonsslgnals M ⁺ with the positive and negative reference signal R ⁺ , R ". After equating the signal domain, one gets analytical expressions for the positive switch-on times

and the negative switch-on points

_t - "J_ _arctan Oo-Üsln (2k-1) n / p ω Go-Ücos (2I <-1) n / p

and the negative switch-on times The pulse time with

tp = Γ ¹ -1 ⁺ then yields

1, 2Ü (G (> slnd (2k - 1 ) n / p - G "cos (2k + 1) n / p tp = - arctan OJ ₊ G ,, '- Ü ^l

The reference signals can be obtained by transforming a complex voltage vector from one with a differential frequency

be obtained rotating coordinate system.

In this case, initially, starting with a complex voltage vector in the rotating coordinate system

a back transformation into the fixed coordinate system is required, which then the pointer

supplies. For the pulse modulation, the positive or negative real part of the voltage vector are used as reference signals

R ⁺ = (Xcosa - Ysina) cos <j) t - (Xsina + Ycosa) sinu) t

= G ₀ COSt -GsSint

R "= (Xcosa - Ysinalcosiot + (Xsina + Ycosa) sln <ot

= · -G _Q cosut -hGpSincot

used.

With a large number of pulses p, d. H. high pulse rate, the above calculated trigonometric functions can be linearized,

so that results

_1_ 2 Cl (Ysin (2 k ~ 1) n / p - X cos (2 k -1) n / p "ω X ² + Y ² -Cl ²

The equation can be with high pulse number ρ with

U ² i> (X ² + Y ² ) further simplify

, 2 (Xcos (2k - 1) n / p - Ysin (2k - 1) n / p _{tp =} - ^

In view of the high computation speeds for the control required at higher pulse frequencies, such a simple analytical calculation is of great advantage. Further advantages compared to the pulse pattern control are the following:

- The phase angles of the individual pulses coincide on average with the phase position of the signal to be converted.

- An amplitude change of the reference signal is converted into the pulse width modulation in conformity, as long as the reference signal is smaller than the modulation signal.

Advantages over conventional undershoot methods in which the sampling of the reference signal with double pulse frequency is made in

- Avoiding false pulses near the zero crossing of the reference signal and

- To see the improved overshoot balance at low pulse counts per fundamental amplitude.

The method is also transferable to multiphase circuits if the assignment of modulation and reference signals is maintained for each phase.

Claims (1)

1. A method for driving a single- or multi-phase converter In bridge circuit with pulse width modulation according to the undershoot method, characterized in that single- or multi-phase reference signals (R ⁺ ; R ~) of the general harmonic form with respective positive and negative signs with sectionwise sinusoidal modulation signals (M ⁺ ; M "), which have one of the pulse number ρ and the amplitude of the reference signal Ü _R dependent amplitude of the size Ü _R / sin (/ p) and the same frequency and its rising edge (M ⁺ ) through the shape