CN201742387U - Single phase-lock loop based on synchronous coordinate system - Google Patents

Abstract

The utility model discloses a single phase-lock loop based on a synchronous coordinate system, comprising a phase discriminator (PD), a loop filter (LF) and a voltage-controlled oscillator (VCO), wherein the phase discriminator (PD) is connected with the loop filter (LF) end to end; the output of the loop filter (LF) is connected with the voltage-controlled oscillator (VCO) after being added to an initial value ohm; the phase discriminator (PD) consists of a virtual signal generating circuit (A) and a Park converter; the virtual signal generating circuit (A) consists of a multiplier (Mul), a low pass filter (LPF) and a trigonometric function calculator (Cal); the input of the low pass filter (LPF) is the output of a d shaft of the Park converter; and the output of the low pass filter (LPF) is connected to an input end of the multiplier (Mul). The single phase phase-lock loop can still acquire the phase of an input signal precisely even under the condition that the frequency of the input signal changes.

Description

A kind of single-phase phase-locked loop based on synchronous coordinate system

Technical field

The utility model relates to single-phase phase-locked loop technology in a kind of electric power system, is particularly useful under the situation of frequency input signal fluctuation, accurately measures the phase place of voltage in the single phase system or electric current.

Background technology

In electric power system, the technical development of three-phase phase-locked loop is very ripe, but abundant not enough for the single-phase phase-locked loop technical research, has problem in various degree.

A basic block diagram of single-phase phase-locked loop as shown in Figure 1.By phase discriminator (PD), loop filter (LF) and voltage controlled oscillator (VCO) are formed.The phase discriminator phase difference output via loop filter filtering control, is given voltage controlled oscillator, and voltage controlled oscillator output feeds back in the phase discriminator, thus the locking phase of input signals.

Common single-phase phase-locked loop is according to the difference of phase discriminator (PD), can be divided into based on the single-phase phase-locked loop of rest frame with based on the single-phase phase-locked loop of synchronous coordinate system.In single phase system, owing to lack an essential input variable based on the single-phase phase-locked loop of synchronous coordinate system, its development is very slow, has many documents to propose single-phase phase-locked loop based on synchronous coordinate system recently abroad.As shown in Figure 2, this phase-locked loop needs two orthogonal input signals, through output phase error after the Park conversion, produces output signal through LF and VCO again.But in single phase system, has only an input signal v _α, need to generate in addition a virtual input signal v _βSome method is by digital memory device storage original input signal v _αWaveform, through 1/4 all after date, again with existing signal together as the input of Park converter.But second virtual signal v that this method produces _βBe not the amount of accurate phase shift 90 degree of present input signal, can not obtain accurate phase place output, and very big delay is arranged.Also some method produces v by external module with input signal phase shift 90 degree abroad _β, but these methods all can't guarantee to produce virtual signal accurately under the situation that frequency input signal changes, and also just can't obtain phase place accurately.If will overcome this situation, need the impressed frequency measuring circuit, but this makes again single-phase phase-locked loop become very complicated, is unfavorable for using.

The utility model content

For overcoming the deficiency that can't under the situation that frequency input signal changes, obtain accurate phase place based on the single-phase phase-locked loop of synchronous coordinate system.The utility model provides a kind of single-phase phase-locked loop based on synchronous coordinate system.This single-phase phase-locked loop not only can be under the condition of mains frequency fluctuation locking phase rapidly and accurately, and this method simple, be easy to hardware and software and realize.

The technical scheme that its technical problem that solves the utility model adopts is:

A kind of single-phase phase-locked loop based on synchronous coordinate system, comprise phase discriminator (PD), loop filter (LF) and voltage controlled oscillator (VCO), described phase discriminator (PD) links to each other with loop filter (LF) front and back, and loop filter (LF) output links to each other with voltage controlled oscillator (VCO); Described phase discriminator (PD) produces circuit (A) by virtual signal and the Park converter constitutes; Described virtual signal produces circuit (A) and is made of multiplier (Mul), low pass filter (LPF) and trigonometric function calculator (Cal); Described low pass filter (LPF) is input as the output of Park converter d axle, and an input of multiplier (Mul) is received in described low pass filter (LPF) output; Described trigonometric function calculator (Cal) is input as the phase place output of single-phase phase-locked loop, and described trigonometric function calculator (Cal) output is as second input of multiplier (Mul).

Described Park converter is the mathematic(al) manipulation module that a kind of two-phase static coordinate is tied to the two-phase rotating coordinate system, and transformation for mula is as follows:

$\left[\begin{array}{c}{x}_d\\ x_q\end{array}\right.0=\left[\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\left[\begin{array}{c}{x}_{\mathrm{\α}}\\ x_{\mathrm{\β}}\end{array}\right]$

X wherein _α, x _βBe respectively rest frame α, the component on the β axle; x _d, x _qBe respectively rotating coordinate system d, the component on the q axle; θ is the angle of d axle and α axle.

Described Park converter also can be a described Park converter commonly used in the prior art.

The beneficial effects of the utility model are, even under the occasion that frequency input signal changes, still can accurately obtain phase of input signals.

Description of drawings

Fig. 1 is a single-phase phase-locked loop basic principle block diagram.

Fig. 2 is based on synchronous coordinate system single-phase phase-locked loop theory diagram.

Fig. 3 is an example schematic diagram of the present utility model.

Fig. 4 is a Park conversion schematic diagram.

Embodiment

As shown in Figure 3, this single-phase phase-locked loop is made up of four parts, comprising: Park converter, loop filter (LF), voltage controlled oscillator (VCO) and virtual signal generation unit (frame of broken lines A).The virtual signal generation unit is made of multiplier (Mul), low pass filter (LPF) and trigonometric function calculator (Cal).Low pass filter (LPF) is input as the output of Park converter d axle, and an input of multiplier (Mul) is received in output; Trigonometric function calculator (Cal) is input as the phase place output of this phase-locked loop, and exports after doing the calculating of trigonometric function, and output is as second input of multiplier.Multiplier is output as the virtual signal of generation.

This virtual signal produces circuit and has made full use of the output phase signal θ of single-phase phase-locked loop itself and the output signal v of Park conversion _d, producing the phase information and the amplitude information of virtual signal respectively, both multiply each other and have just constructed and input signal v _αPerpendicular virtual signal v _β, and second input signal of virtual generation change along with the frequency change of input signal, becomes 90 degree relations all the time with original input signal.Low pass filter (LPF) is used for filtering dynamic process v _dOn ripple, obtain amplitude information accurately.Virtual signal generation circuit and Park converter have constituted phase discriminator (PD) link accurately jointly like this.And PD, LF and VCO are exactly an all elements that phase-locked loop is required, so the circuit of this structure can be measured phase of input signals accurately.

In Fig. 4, two kinds of coordinate systems are arranged: static α β coordinate system and synchronous dq rotating coordinate system.Synchronous coordinate system with vectorial V _sSame angular speed rotation.The transformation relation formula that is tied to synchronous coordinate system by static coordinate is as follows:

$\left[\begin{array}{c}{v}_d\\ v_q\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\left[\begin{array}{c}{v}_{\mathrm{\α}}\\ v_{\mathrm{\β}}\end{array}\right]$

This conversion of being described by above formula that is tied to the two-phase synchronous coordinate system by the two-phase static coordinate is just named Park conversion.The Park conversion needs two mutually perpendicular amount v _α, v _βSuppose v _αBe actual input signal, its expression formula is:

v _α＝Ucosωt

If the second virtual input variable is:

v _β＝Usin(ωt)

Pass through after the Park conversion v so _d, v _qFor:

$\left[\begin{array}{c}{v}_d\\ v_q\end{array}\right]=\left[\begin{array}{cc}\cos \left(\widehat{\mathrm{\ω}}t\right)& \sin \left(\widehat{\mathrm{\ω}}t\right)\\ -\sin \left(\widehat{\mathrm{\ω}}t\right)& \cos \left(\widehat{\mathrm{\ω}}t\right)\end{array}\right]\left[\begin{array}{c}U\cos \left(\mathrm{\ωt}\right)\\ U\sin \left(\mathrm{\ωt}\right)\end{array}\right]=U\left[\begin{array}{c}\cos (\mathrm{\ωt}-\widehat{\mathrm{\ω}}t)\\ \sin (\mathrm{\ωt}-\widehat{\mathrm{\ω}}t)\end{array}\right]$

At phase-locked loop output phase during near stable state Approximate input signal phase place ω t.D, q axle component become respectively like this:

$\left[\begin{array}{c}{v}_d\\ v_q\end{array}\right]=U\left[\begin{array}{c}\cos (\mathrm{\ωt}-\widehat{\mathrm{\ω}}t)\\ \sin (\mathrm{\ωt}-\widehat{\mathrm{\ω}}t)\end{array}\right]\≈\left[\begin{array}{c}U\\ U(\mathrm{\ωt}-\widehat{\mathrm{\ω}}t)\end{array}\right]$

As can be seen through after the Park conversion, during near stable state, d axle component v _dActual is exactly the amplitude of input signal, q axle component v _qIt is exactly phase error signal.Utilize the phase place and the d axle component of phase-locked loop output itself, can reconstruct another signal v vertical with input signal _β=Usin (ω t).Because this signal has directly utilized phase of input signals, so vertical with input signal all the time.The signal v of reconstruct _βWith input signal v _αObtain phase error through behind the Park converter, pass through phase-lockedly again, just can obtain the accurate phase information of input signal.

In the application example of Fig. 3, input signal is not for containing the signal of harmonic wave.Virtual signal produces circuit (frame of broken lines A) and has produced a virtual signal Usin vertical with input signal (ω t), and this signal is as another input of Park converter.So just guaranteed that the Park conversion has mutually perpendicular signal, thereby phase-locked loop can access phase place output accurately.

Above content is to further describing that the utility model is done in conjunction with concrete preferred implementation; can not assert that embodiment of the present utility model only limits to this; for the utility model person of an ordinary skill in the technical field; under the prerequisite that does not break away from the utility model design; can also make some simple deduction or replace, all should be considered as belonging to the utility model and determine scope of patent protection by claims of being submitted to.

Claims (2)

1. single-phase phase-locked loop based on synchronous coordinate system, comprise phase discriminator (PD), loop filter (LF) and voltage controlled oscillator (VCO), it is characterized in that: described phase discriminator (PD) links to each other with loop filter (LF) front and back, and loop filter (LF) output links to each other with voltage controlled oscillator (VCO); Described phase discriminator (PD) produces circuit (A) by virtual signal and the Park converter constitutes; Described virtual signal produces circuit (A) and is made of multiplier (Mul), low pass filter (LPF) and trigonometric function calculator (Cal); Described low pass filter (LPF) is input as the output of Park converter d axle, and an input of multiplier (Mul) is received in described low pass filter (LPF) output; Described trigonometric function calculator (Cal) is input as the phase place output of single-phase phase-locked loop, and described trigonometric function calculator (Cal) output is as second input of multiplier (Mul).

2. a kind of according to claim 1 single-phase phase-locked loop based on synchronous coordinate system is characterized in that: described Park converter is the mathematic(al) manipulation module that a kind of two-phase static coordinate is tied to the two-phase rotating coordinate system, and transformation for mula is as follows:

$\left[\begin{array}{c}{x}_d\\ x_q\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\left[\begin{array}{c}{x}_{\mathrm{\α}}\\ x_{\mathrm{\β}}\end{array}\right]$

X wherein _α, x _βBe respectively rest frame α, the component on the β axle; x _d, x _qBe respectively rotating coordinate system d, the component on the q axle; θ is the angle of d axle and α axle.

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