CN102931980A - Digital phase-locking loop based on resonance filtering - Google Patents

Digital phase-locking loop based on resonance filtering Download PDF

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CN102931980A
CN102931980A CN2012104311867A CN201210431186A CN102931980A CN 102931980 A CN102931980 A CN 102931980A CN 2012104311867 A CN2012104311867 A CN 2012104311867A CN 201210431186 A CN201210431186 A CN 201210431186A CN 102931980 A CN102931980 A CN 102931980A
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phase
locked loop
resonator
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李阳春
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ZHEJIANG HRV ELECTRIC CO Ltd
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ZHEJIANG RIFENG ELECTRICAL CO Ltd
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Abstract

The invention discloses a digital phase-locking loop based on resonance filtering. The digital phase-locking loop comprises a phase discriminator, a digital filter, a full-wave integrator and a positive-sequence integrator, wherein the digital filter comprises a summator, a subtracter, a integral controller, a proportional controller and a resonator. The digital phase-locking loop is based on a single synchronous coordinate, when a three-phase signal is not balanced, and the positive-sequence weight of the signal is tracked effectively; and compared with a digital phase-locking loop which is based on double synchronous coordinates, the phase-locking loop is low in calculation and is suitable for being used in a real-time control system.

Description

A kind of digital phase-locked loop based on resonator, filter
Technical field
The invention belongs to the digital lock-in technique field, be specifically related to a kind of digital phase-locked loop based on resonator, filter.
Background technology
Phase-locked loop is a kind of frequency and phase locked technology of utilizing feedback control principle to realize, and its effect is to make the output of the module input signal outside with it keep synchronous on the phase place.When the frequency of input signal or phase generate changed, phase-locked loop can detect this variation, and by voltage controlled oscillator regulation output frequency, until both re-synchronizations.PHASE-LOCKED LOOP PLL TECHNIQUE is used widely in fields such as communication, navigation, Broadcast and TV, Digital Signal Processing.
Phase-locked loop can be divided into analog phase-locked look and digital phase-locked loop, and the advantage of digital phase-locked loop is many comparatively speaking, and stable performance, error are little.As shown in Figure 1, a feedback loop being formed by phase discriminator, loop filter, voltage controlled oscillator and frequency divider of the digital phase-locked loop module of prior art.Phase discriminator is for detection of the phase difference of the feedback signal that goes out the output of reference clock and frequency divider; Loop filter is generally low pass filter, and its effect is the aignal averating that contains ripple with phase discriminator output; Voltage controlled oscillator is a kind of variable-frequency oscillator, and according to the direct current signal control frequency of oscillation of input, the signal part that it provides is as output, and another part outputs to phase discriminator again and carries out the phase bit comparison with the reference clock input by behind the frequency divider frequency division.Constant for holding frequency, require phase difference not change, if phase difference changes, then the voltage of the voltage output end of phase-locked loop changes, and FEEDBACK CONTROL voltage controlled oscillator again is until phase difference recovers, can realize the N frequency multiplication of output signal, reach phase-locked purpose.At present, digital phase-locked loop mainly is divided into based on the digital phase-locked loop of single synchronous coordinate system with based on digital phase-locked loop two classes of two Synchronous Reference Frame Transforms.
Based on the digital phase-locked loop of single synchronous coordinate system, this phase-locked loop is based on the positive sequence component of following the tracks of line voltage and the detection algorithm that proposes, and when the line voltage balance, this phase-locked loop is detection of grid voltage-phase, frequency fast and effeciently.As shown in Figure 2, the principle of this phase-locked loop is: three-phase input voltage obtains u after single dq coordinate transform dAnd u q, for u qClosed-loop control adopt the PI controller to eliminate deviation.Work as u q, can realize that output phase and electric network voltage phase are synchronous at=0 o'clock.Owing to adopt closed-loop control, can obtain good phase-locked performance.This algorithm can be obtained good effect under the condition of three-phase voltage balance, but when imbalance of three-phase voltage, the Phase Tracking effect is relatively poor.
Based on the digital phase-locked loop of two Synchronous Reference Frame Transforms, this phase-locked loop is based on the positive sequence component of following the tracks of line voltage and the detection algorithm that proposes, line voltage balance whether no matter, and this algorithm can both fast detecting goes out phase place, the frequency of line voltage positive sequence component.As shown in Figure 3, the operation principle of this phase-locked loop is: the dq that three-phase voltage signal is carried out respectively under positive sequence, two reference axis of negative phase-sequence changes, and utilize the transformation result under the negative phase-sequence reference axis to eliminate two harmonics that produce when the positive-sequence coordinate axle is changed, thereby suppressed the impact of negative sequence component on phase-locked result.The amount of calculation of this algorithm is quite large, in the system of in real time control of needs, affects the real-time of system's control.
Summary of the invention
For the existing above-mentioned technological deficiency of prior art, the invention provides a kind of digital phase-locked loop based on resonator, filter, when imbalance of three-phase voltage, can effectively follow the tracks of out the phase place of its positive sequence phase place and positive-negative sequence component sum, and operand is less.
A kind of digital phase-locked loop based on resonator, filter comprises: phase discriminator, digital filter, full-wave integrator and positive sequence integrator; Wherein:
Described phase discriminator is used for according to the feedback phase of full-wave integrator output three-phase voltage being carried out dq conversion (synchronously rotating reference frame conversion), obtains d axle component and q axle component;
Described digital filter is used for described q axle component is carried out bandpass filtering, obtains all-wave controlled quentity controlled variable and positive sequence controlled quentity controlled variable;
Described full-wave integrator is used for described all-wave controlled quentity controlled variable is carried out integration, produces feedback phase;
Described positive sequence integrator is used for described positive sequence controlled quentity controlled variable is carried out integration, output positive sequence phase place.
The transfer function of described full-wave integrator and positive sequence integrator is 1/s, and s is laplace operator.
Described digital filter comprises: two adders, a subtracter, an integral controller, a proportional controller and resonators; Wherein: the subtrahend end of subtracter links to each other with phase discriminator and receives q axle component, the minuend termination of subtracter is received given reference component, the output of subtracter and the input of integral controller, the input of the input resonator of proportional controller links to each other, the output of integral controller links to each other with the first input end of adder J1 and the first input end of adder J2, the output of proportional controller links to each other with the second input of adder J1 and the second input of adder J2, the output of resonator links to each other with the 3rd input of adder J1, the four-input terminal of adder J1 and the 3rd input of adder J2 all receive given phase increment, the output of adder J1 links to each other with full-wave integrator and exports the all-wave controlled quentity controlled variable, and the output of adder J2 links to each other with the positive sequence integrator and exports the positive sequence controlled quentity controlled variable.
The transfer function of described resonator is as follows:
K R × 2 ω c s s 2 + 2 ω c s + ω o 2
Wherein, K RBe resonance coefficient, ω oBe resonance frequency, ω cBe resonant bandwidth, s is laplace operator.
The transfer function of described integral controller is K I/ s, K IBe integral coefficient, s is laplace operator.
The transfer function of described proportional controller is K P, K PBe proportionality coefficient.
When imbalance of three-phase voltage, line voltage can be decomposed into positive sequence component, negative sequence component and zero-sequence component.By the principle of coordinate transform as can be known, three-phase imbalance voltage carried out the dq conversion after, zero-sequence component vanishing (it can not impact the work of phase-locked loop), positive sequence component will become direct current signal, negative sequence component will become two frequency multiplication signals.Traditional integral element that adopts based on the digital phase-locked loop of single synchronous coordinate system can't be carried out the indifference tracking to two frequency multiplication signals, therefore there is deviation in the Phase Tracking of unbalance voltage.
The present invention has increased a resonance link on the basis based on single synchronous coordinate system digital phase-locked loop, its resonance frequency just is set to two frequencys multiplication (100Hz), thereby has realized the indifference of two frequency multiplication signals is followed the tracks of, and reaches accurately phase-locked purpose.
So digital phase-locked loop of the present invention with respect to the digital phase-locked loop based on single synchronous coordinate, can effectively be followed the tracks of out its positive sequence component when three-phase signal is uneven; With respect to the digital phase-locked loop based on two synchronous coordinates, the operand of this phase-locked loop is less, is more suitable for using in real-time control system.
Description of drawings
Fig. 1 is the structural representation of conventional digital phase-locked loop.
Fig. 2 is the structural principle schematic diagram based on the digital phase-locked loop of single synchronous coordinate system.
Fig. 3 is the structural principle schematic diagram based on the digital phase-locked loop of two synchronous coordinate systems.
Fig. 4 is the structural principle schematic diagram of digital phase-locked loop of the present invention.
Fig. 5 is for adopting the Phase Tracking oscillogram based on the phase-locked loop of single synchronous coordinate.
Fig. 6 is for adopting the Phase Tracking oscillogram of phase-locked loop of the present invention.
Embodiment
In order more specifically to describe the present invention, below in conjunction with the drawings and the specific embodiments technical scheme of the present invention and relative theory thereof are elaborated.
As shown in Figure 4, a kind of digital phase-locked loop based on resonator, filter comprises: phase discriminator, digital filter, full-wave integrator and positive sequence integrator; Wherein:
The feedback phase θ ' that phase discriminator is used for exporting according to full-wave integrator is to three-phase voltage u a～u cCarry out the dq conversion, obtain d axle component u dWith q axle component u q
Three-phase voltage signal u a～u cCan be expressed as following form:
Wherein: With
Figure BDA00002343573700043
Be respectively positive sequence and negative phase-sequence fundamental signal peak value;
Figure BDA00002343573700044
With Be respectively the starting phase angle of positive sequence and negative phase-sequence fundamental signal.
Can be with three-phase voltage signal u according to following conversion formula a～u cConvert the α axle component u under the α β coordinate system to αWith beta-axis component u β:
Figure BDA00002343573700046
And then according to feedback phase θ ' by following conversion formula, with α axle component u αWith beta-axis component u βConvert the d axle component u under the dq coordinate system to dWith q axle component u q:
u d u q = cos θ ′ sin θ ′ - sin θ ′ cos θ ′ u α u β
Figure BDA00002343573700048
Because our target is to make the θ ' should be approaching as far as possible So can be with the following formula arrangement:
Figure BDA000023435737000410
Wherein:
Figure BDA00002343573700051
u qOutput as phase discriminator.
As can be seen from the above equation, this output u qWith larger two harmonics.
Digital filter is used for q axle component u qCarry out bandpass filtering, obtain all-wave controlled quentity controlled variable and positive sequence controlled quentity controlled variable; Because the output of phase discriminator contains the component of two a large amount of frequencys multiplication, this two harmonic is to be produced by the negative sequence component in the input signal; The existence of this two harmonic has produced certain interference to the positive sequence component of following the tracks of input signal.
So present embodiment utilizes respectively integration, resonance algorithm that DC component and two harmonics are controlled respectively filtering in digital filter.Digital filter comprises two adder J1～J2, a subtracter Z, an integral controller, a proportional controller and a resonator; Wherein: the subtrahend end of subtracter Z links to each other with phase discriminator and receives q axle component u qThe minuend termination of subtracter Z is received given reference component (reference component is 0), the output of subtracter Z and the input of integral controller, the input of the input resonator of proportional controller links to each other, the output of integral controller links to each other with the first input end of adder J1 and the first input end of adder J2, the output of proportional controller links to each other with the second input of adder J1 and the second input of adder J2, the output of resonator links to each other with the 3rd input of adder J1, and the four-input terminal of adder J1 and the 3rd input of adder J2 all receive given phase increment ω f(when sample frequency is 12KHz, phase increment ω f=1.5 °), the output of adder J1 links to each other with full-wave integrator and exports the all-wave controlled quentity controlled variable, and the output of adder J2 links to each other with the positive sequence integrator and exports the positive sequence controlled quentity controlled variable.
The transfer function of resonator is as follows:
K R × 2 ω c s s 2 + 2 ω c s + ω o 2
Wherein, K RBe resonance coefficient, ω oBe resonance frequency, ω cBe resonant bandwidth, s is laplace operator; In the present embodiment, K R=1, ω o=100Hz, ω c=30Hz.
The transfer function of integral controller is K I/ s, K IBe integral coefficient; In the present embodiment, K I=0.3.
The transfer function of proportional controller is K P, K PBe proportionality coefficient; In the present embodiment, K P=1.5.
Full-wave integrator is used for the all-wave controlled quentity controlled variable is carried out integration, produces feedback phase θ '; Its waveform is consistent with the positive-negative sequence component sum of input waveform.
The positive sequence integrator is used for the positive sequence controlled quentity controlled variable is carried out integration, output positive sequence phase theta; Its waveform is consistent with the positive sequence component of input waveform.
In the present embodiment, the transfer function of full-wave integrator and positive sequence integrator is 1/s.
Below follow the tracks of waveform by actual phase present embodiment and the phase-locked loop of tradition based on single synchronous coordinate compared, and it is as follows to input identical three-phase voltage signal:
Figure BDA00002343573700061
Employing is based on the phase-locked loop of single synchronous coordinate, and the tracking waveform of its phase place as shown in Figure 5; Adopt the phase-locked loop of present embodiment, the tracking waveform of its phase place as shown in Figure 6; Can find out by two figure contrasts, the tracking error of the digital phase-locked loop of present embodiment is about 6 degree, and owing to can only follow the tracks of positive sequence component based on the digital phase-locked loop of single synchronous coordinate system, therefore its tracking error mean value will level off to 60 degree, its error amplitude is about 40 degree, and the tracking accuracy of the digital phase-locked loop of present embodiment that hence one can see that is higher than the digital phase-locked loop based on single synchronous coordinate system far away.
When imbalance of three-phase voltage, line voltage can be decomposed into positive sequence component, negative sequence component and zero-sequence component.By the principle of coordinate transform as can be known, three-phase imbalance voltage carried out the dq conversion after, zero-sequence component vanishing (it can not impact the work of phase-locked loop), positive sequence component will become direct current signal, negative sequence component will become two frequency multiplication signals.Traditional integral element that adopts based on the digital phase-locked loop of single synchronous coordinate system can't be carried out the indifference tracking to two frequency multiplication signals, therefore there is deviation in the Phase Tracking of unbalance voltage.
Present embodiment has increased a resonance link on the basis based on single synchronous coordinate system digital phase-locked loop, its resonance frequency just is set to two frequencys multiplication (100Hz), thereby has realized the indifference of two frequency multiplication signals is followed the tracks of, and reaches accurately phase-locked purpose.
So the present embodiment digital phase-locked loop with respect to the digital phase-locked loop based on single synchronous coordinate, can effectively be followed the tracks of out its positive sequence component when three-phase signal is uneven; With respect to the digital phase-locked loop based on two synchronous coordinates, the operand of this phase-locked loop is less, is more suitable for using in real-time control system.
The description of present embodiment is can understand and apply the invention for ease of those skilled in the art.The person skilled in the art obviously can easily make various modifications to these embodiment, and needn't pass through performing creative labour being applied in the General Principle of this explanation among other embodiment.Therefore, the invention is not restricted to the embodiment here, those skilled in the art should be within protection scope of the present invention for improvement and modification that the present invention makes according to announcement of the present invention.

Claims (9)

1. the digital phase-locked loop based on resonator, filter is characterized in that, comprising: phase discriminator, digital filter, full-wave integrator and positive sequence integrator; Wherein:
Described phase discriminator is used for according to the feedback phase of full-wave integrator output three-phase voltage being carried out the dq conversion, obtains d axle component and q axle component;
Described digital filter is used for described q axle component is carried out bandpass filtering, obtains all-wave controlled quentity controlled variable and positive sequence controlled quentity controlled variable;
Described full-wave integrator is used for described all-wave controlled quentity controlled variable is carried out integration, produces feedback phase;
Described positive sequence integrator is used for described positive sequence controlled quentity controlled variable is carried out integration, output positive sequence phase place.
2. the digital phase-locked loop based on resonator, filter according to claim 1, it is characterized in that: the transfer function of described full-wave integrator and positive sequence integrator is 1/s, and s is laplace operator.
3. the digital phase-locked loop based on resonator, filter according to claim 1, it is characterized in that: described digital filter comprises: two adders, a subtracter, an integral controller, a proportional controller and resonators; Wherein: the subtrahend end of subtracter links to each other with phase discriminator and receives q axle component, the minuend termination of subtracter is received given reference component, the output of subtracter and the input of integral controller, the input of the input resonator of proportional controller links to each other, the output of integral controller links to each other with the first input end of adder J1 and the first input end of adder J2, the output of proportional controller links to each other with the second input of adder J1 and the second input of adder J2, the output of resonator links to each other with the 3rd input of adder J1, the four-input terminal of adder J1 and the 3rd input of adder J2 all receive given phase increment, the output of adder J1 links to each other with full-wave integrator and exports the all-wave controlled quentity controlled variable, and the output of adder J2 links to each other with the positive sequence integrator and exports the positive sequence controlled quentity controlled variable.
4. the digital phase-locked loop based on resonator, filter according to claim 3, it is characterized in that: the transfer function of described resonator is as follows:
K R × 2 ω c s s 2 + 2 ω c s + ω o 2
Wherein, K RBe resonance coefficient, ω oBe resonance frequency, ω cBe resonant bandwidth, s is laplace operator.
5. the digital phase-locked loop based on resonator, filter according to claim 3, it is characterized in that: the transfer function of described integral controller is K I/ s, K IBe integral coefficient, s is laplace operator.
6. the digital phase-locked loop based on resonator, filter according to claim 3, it is characterized in that: the transfer function of described proportional controller is K P, K PBe proportionality coefficient.
7. the digital phase-locked loop based on resonator, filter according to claim 4, it is characterized in that: described resonance coefficient gets 1, and described resonance frequency is got 100Hz, and described resonant bandwidth is got 30Hz.
8. the digital phase-locked loop based on resonator, filter according to claim 5, it is characterized in that: described integral coefficient gets 0.3.
9. the digital phase-locked loop based on resonator, filter according to claim 6, it is characterized in that: described proportionality coefficient gets 1.5.
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Cited By (2)

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CN113810047A (en) * 2021-11-17 2021-12-17 浙江日风电气股份有限公司 Signal phase locking method and system
US20230253972A1 (en) * 2022-02-07 2023-08-10 Kabushiki Kaisha Toshiba Resonance frequency detector and sensing device

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CN101820281A (en) * 2010-04-15 2010-09-01 西安交通大学 Single-phase phase locked loop based on double-park transformation phase discriminator and implement method thereof

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113810047A (en) * 2021-11-17 2021-12-17 浙江日风电气股份有限公司 Signal phase locking method and system
CN113810047B (en) * 2021-11-17 2022-03-01 浙江日风电气股份有限公司 Signal phase locking method and system
US20230253972A1 (en) * 2022-02-07 2023-08-10 Kabushiki Kaisha Toshiba Resonance frequency detector and sensing device
US12095469B2 (en) * 2022-02-07 2024-09-17 Kabushiki Kaisha Toshiba Resonance frequency detector and sensing device

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