Power phase checkout gear and detection method in a kind of energy back feed device
Technical field
The present invention relates to a kind of power phase checkout gear and detection method, specifically, relate to power phase checkout gear and detection method in a kind of energy back feed device.
Background technology
The energy back feed device system construction that industry is used always as shown in Figure 1, its basic functional principle all is the phase place that control circuit passes through the detection of grid power supply, triggering the conducting of power power electronic element turn-offs, realize that direct current flows to AC network, when current phase and electric network voltage phase difference are spent greater than 90, realized that energy is transmitted back to electrical network.
The phase-detection link is to realize the key of the correct loopback electrical network of energy, and generally, it is made of transformer, filter and last several parts of power phase testing circuit, shown in empty frame part among Fig. 1.
Wherein transformer mainly plays and isolates and the effect of step-down, generally adopts Y/Y structure or Δ/Δ structure, when guaranteeing former secondary voltage phase place unanimity supply voltage is isolated and step-down; Power electronic device copped wave produced when filter was mainly worked for the filtering feedback system interference signal and electrical network clutter, in order electrical network power-frequency voltage signal not to be produced phase shift, the filter circuit that filter adopts only carries out filtering at the interference signal more than the 2KHz usually, feedback system is under the normal situation of line voltage, the processing procedure of mains voltage signal as shown in Figure 2, voltage waveform corresponds respectively to A, B, C 3 points of Fig. 1 mark; Last power phase testing circuit is by detecting the phase place that obtains line voltage through the zero crossing of the voltage signal after isolated buck and the Filtering Processing.
When serious distortion took place line voltage, voltage waveform may become the appearance shown in Fig. 3 dotted line.Because the phase shift that Harmonic Interference and filter cause makes voltage over zero change, or even is beating, t1 does not overlap (dotted line is represented the mains voltage signal that distorts and contain burr to disturb, and solid line is represented the mains voltage signal of standard) with t2.
For above-mentioned reasons, when grid voltage waveform distorts when serious, it is inaccurate that the detection method of zero crossing can cause energy back feed device that power phase is detected, and feedback device can't operate as normal.
In order to obtain the sine voltage signal of standard, generally the parameter of filter is adjusted, carry out filtering such as the method that can adopt single order or second-order low-pass filter circuit, when low-order harmonic content is bigger, the method that increases the low-pass filtering time constant can obtain the fundamental signal of supply voltage, but can cause bigger phase shift simultaneously, detection signal can't react the true phase place of power supply, the feedback ability of feedback device descends greatly in such cases, even causing serious fault, wave form varies is as shown in Figure 4.
In addition, adopt the method for resonator, filter to carry out filtering at the harmonic wave of a certain frequency; For low-order harmonic, inductance parameters is bigger, and the volume heating all has problem, owing to adopted the RLC element, also causes phase shift simultaneously, and the parameter matching complexity, very flexible.
Also can adopt digital filtering mode to achieve the goal, in Fig. 2, omit hardware filtering device link, after power phase testing circuit part will directly be carried out the A/D conversion by the power supply voltage signal after the transformer step-down, carry out Fourier decomposition, adopt digital filtering method to extract fundamental signal, also can obtain the phase signal of power supply, but digital signal processing devices such as needs employing DSP just can be finished, the cost height is easily introduced digital circuit with interference signal simultaneously.
Summary of the invention
Power phase checkout gear and detection method in a kind of energy back feed device that the present invention designs in order to solve the problems of the technologies described above just, but correct network voltage detection phase place obtained its filtering low-order harmonic the time.
The technical solution adopted for the present invention to solve the technical problems is:
Power phase checkout gear in a kind of energy back feed device comprises feedback power circuit, feedback control circuit, phase shifting transformer, low-pass filter circuit and power phase testing circuit; Line voltage (U
i) export to low-pass filter circuit through phase shifting transformer, give the power phase testing circuit after the low-pass filter circuit filtering, thereby export to feedback control circuit control feedback power circuit at last; Obtain leading phase shift by phase shifting transformer, low-pass filter circuit produces the hysteresis phase shift, by behind both composition complementaries the power supply first-harmonic not being produced phase shift.
Power phase checkout gear in described a kind of energy back feed device, its phase shifting transformer adopt Y/ Δ connection, or adopt Δ/Y connection, by adjusting phase sequence, can obtain leading phase π/6.
Power phase checkout gear in described a kind of energy back feed device, its phase shifting transformer adopts former limit Y or Δ connection, phase shifting transformer adopts pays limit extend-triangle connection, can obtain the leading phase of different angles, leading phase is big more, and the time constant filter of low-pass filter circuit is can selectivity bigger.
Power phase checkout gear in described a kind of energy back feed device, its low-pass filter circuit carries out filtering to this signal, and by adjusting time constant filter, it produces arbitrarily angled hysteresis phase shift to fundamental signal.
Power phase checkout gear in described a kind of energy back feed device, its low-pass filter circuit carries out filtering to this signal, and it can cause decay to harmonic wave more than three times.
Power phase checkout gear in described a kind of energy back feed device, its phase detecting circuit are relatively to obtain the supply voltage phase place by voltage zero-cross.
Power phase checkout gear in described a kind of energy back feed device, its low-pass filter circuit are the active or passive filtering of single order, or multistage active or passive filtering.
Power phase checkout gear in described a kind of energy back feed device, its phase shifting transformer and low-pass filter circuit position relation each other can exchange.
Power phase detection method in a kind of energy back feed device, its phase-detection are according to following works:
1. line voltage (the U that contains harmonic wave
i) the phase shift effect of signal by phase shifting transformer, obtain the leading voltage signal of phase place; In order to guarantee that phase shifting transformer carries out leading phase shift to voltage, can adopt circuit of testing the phase sequence that the line voltage phase sequence that inserts is detected, what guarantee access is correct phase sequence;
2. by the filter action of low-pass filter circuit, the harmonic signal more than 3 times is carried out algorithm, simultaneously the fundamental signal phase place is produced the hysteresis phase shift, the electric network voltage phase detection signal (U of final acquisition and line voltage same phase
S);
3. the power phase testing circuit obtains power phase accurately by the zero crossing of detection with the synchronous voltage signal of electrical network, offers the feedback control circuit and uses.
The invention has the beneficial effects as follows: power phase checkout gear cost is low, simple in structure in this energy back feed device, good wave filtering effect, and when power supply was realized isolation, step-down, filtering, detection signal did not produce phase shift to the power supply first-harmonic.The power phase detection method can effectively improve the operating efficiency and the functional reliability of energy back feed device in this energy back feed device, to the adaptive capacity enhancing of line voltage.
Description of drawings
Fig. 1 is the energy back feed device system block diagram.
Fig. 2 is the mains voltage signal processing procedure oscillogram under the undistorted situation of line voltage.
Fig. 3 causes zero crossing offset wave forms figure for the line voltage distortion.
Fig. 4 adopts under the line voltage distortion situation to adjust filter parameter mode processing procedure oscillogram.
Fig. 5 is the mains voltage signal processing procedure oscillogram of band phase compensation.
Fig. 6 is the electric network voltage phase detection system block diagram of band phase compensation.
Embodiment
The present invention is further described below in conjunction with drawings and Examples.
As shown in Figure 6, power phase checkout gear in a kind of energy back feed device of the present invention comprises feedback power circuit, feedback control circuit, phase shifting transformer, low-pass filter circuit and power phase testing circuit.Line voltage is exported to low-pass filter circuit through Y/ Δ phase shifting transformer, judges the line voltage phase sequence by circuit of testing the phase sequence, knows that the phase shifting transformer output phase changes; Give the power phase testing circuit after the low-pass filter circuit filtering, thereby export to feedback control circuit control feedback power circuit at last.
Power phase checkout gear in described a kind of energy back feed device, its circuit of testing the phase sequence detection of grid is as line voltage (U
i) phase sequence is timing, phase shifting transformer makes transformer pay the leading former limit π of limit output phase/6; When the line voltage phase sequence when negative, phase shifting transformer makes transformer pay limit output phase former limit π/6 that lag behind.
Power phase checkout gear in described a kind of energy back feed device, Y or Δ connection are adopted in the former limit of phase shifting transformer, pay the limit and adopt the extend-triangle connection, can obtain the leading phase of different angles, leading phase is big more, the time constant filter of low-pass filter circuit is can selectivity bigger, the convenient simultaneously above filter circuit in two rank, the better effects if of adopting.
Power phase checkout gear in described a kind of energy back feed device, its low-pass filter circuit carries out filtering to this signal, and it is to fundamental signal phase shift hysteresis π/6.
Power phase checkout gear in described a kind of energy back feed device, its low-pass filter circuit carries out filtering to this signal, and it can cause decay to harmonic wave more than three times.
Power phase checkout gear in described a kind of energy back feed device, its phase detecting circuit are relatively to obtain the supply voltage phase place by voltage zero-cross.
Power phase checkout gear in described a kind of energy back feed device, its filter circuit are the active or passive filtering of single order, or multistage active or passive filtering.
Power phase checkout gear in described a kind of energy back feed device, its phase shifting transformer and filter circuit position relation each other can exchange.
As shown in Figure 5, power phase detection method in described a kind of energy back feed device, its phase-detection are according to following works:
1. line voltage (the U that contains harmonic wave
i) the phase shift effect of signal by phase shifting transformer, obtain the leading voltage signal of phase place; In order to guarantee that phase shifting transformer carries out leading phase shift to voltage, shown in Fig. 5 (B), adopt circuit of testing the phase sequence that the line voltage phase sequence that inserts is detected, what guarantee access is correct phase sequence.
2. by the filter action of low-pass filter circuit, the harmonic signal more than 3 times is carried out algorithm, simultaneously the fundamental signal phase place is produced the hysteresis phase shift, the electric network voltage phase detection signal (U of final acquisition and line voltage same phase
S); The sinusoidal degree of this signal improves greatly, supplies with phase detecting circuit and uses, shown in Fig. 5 (C).
3. the power phase testing circuit obtains power phase accurately by the zero crossing of detection with the synchronous voltage signal of electrical network, offers the feedback control circuit and uses.
The present invention is not limited to above-mentioned preferred forms, and other any identical with the present invention or akin products that anyone draws under enlightenment of the present invention all drop within protection scope of the present invention.