Voltage automatic control type electric energy feedback device
Affiliated technical field
The utility model relates to the power-converting device that a kind of direct current power input is transformed to AC power output, belongs to energy conversion and electric and electronic technical field.Be the voltage automatic control type electric energy feedback device of the loopback of DC power supply energy being given AC network specifically.
Technical background
Motor can four quadrant running, and when alternating current motor was operated in on-position, alternating current motor can change the mechanical energy of load into AC energy.When adopting the running under braking of voltage frequency converter control ac motor speed control, the AC energy that can be changed by load machinery converts direct current energy to by voltage frequency converter and leaves in the storage capacitor in the voltage frequency converter DC loop, because storage capacitor finite capacity, must in time discharge the electric energy in the storage capacitor, otherwise the voltage of storage capacitor can raise rapidly, causes frequency converter overvoltage fault.The method that present voltage frequency converter generally adopts resistance to consume energy discharges the electric energy in the storage capacitor, the shortcoming of this method is that the AC energy that mechanical energy changes is depleted in the resistance in vain, the overall system decrease in efficiency, and cause power consumption resistance seriously to generate heat, influence the ambient temperature of operational outfit periphery.Therefore, how with this part electric energy high efficiency, contamination-freely to feed back to AC network be current anxious problem to be solved.
Though adopt the alterating and direct current flow pattern frequency converter of thyristor can make the thyristor of ac-dc conversion be operated in the active inversion state, the function of AC network is given the direct current energy loopback in the DC loop energy storage inductor in realization, but the thyristor active inversion feeds back to direct current energy in You Hen Da De Harmonic ripple electric current in the process of AC network, the active inversion top that power factor Di , Harmonic wave interference causes makes the reliability of system works reduce again.And the variation of ac grid voltage may cause refusing feedback or missing feedback of electric energy.That is, when ac grid voltage was on the low side, the frequency converter dc voltage was also on the low side, may cause refusing feedback or postponing feedback of electric energy, and when ac grid voltage was higher, the frequency converter dc voltage was also higher, may cause the mistake feedback of electric energy,
Summary of the invention
The purpose of this utility model is defective and the deficiency that overcomes prior art, providing a kind of has High Power Factor, Di Harmonic ripple electric current and can monitor to realize self adaptation work, the tangible voltage automatic control type of power savings electric energy feedback device ac grid voltage and DC power supply.
Technical solution of the present utility model is: voltage automatic control type electric energy feedback device, include source inventer, external dc power is connected with the input of active inverter with capacitive storage circuit through the isolating diode loop, and the output of active inverter is connected with AC network through the LC filter.
Active inverter of the present utility model is a three-phase controllable type active inverter, and its control end is connected with voltage control loop.
Voltage control loop of the present utility model is by current control circuit, the alternating voltage control circuit, dc voltage control circuit, voltage adaptive control circuit and isolated drive circuit are formed, the signal input part of voltage adaptive control circuit respectively with current control circuit, the alternating voltage control circuit, dc voltage control circuit connects, the output of voltage adaptive control circuit is connected with the input of isolated drive circuit, and the output of isolated drive circuit is connected with the control end of three-phase controllable type active inverter.
The current sample device that two magnetic in the current control circuit of the present utility model are isolated or light is isolated is connected with two-phase power supply on the AC network respectively, have the input of an anti-phase adder in parallel with the signal output part of current sample device respectively through resistance, the output of current sample device and anti-phase adder inserts the voltage adaptive control circuit.
One anti-phase adder is arranged in the dc voltage control circuit of the present utility model, and the input of anti-phase adder is in parallel with an end of DC power supply through electric capacity, and the two ends of DC power supply and the output of anti-phase adder insert the voltage adaptive control circuit.
The input of voltage adaptive control circuit of the present utility model is connected with two-phase power supply on the AC network through rectifier bridge.
Compared with prior art, the beneficial effects of the utility model are: 1, can solve the defective that the thyristor active inverter exists well, and realize the electric energy feedback AC network of High Power Factor, Di Harmonic ripple electric current.2, adopt three-phase controllable type active inverter and inserted voltage control loop, pass through the information such as alternating voltage, direct voltage, DC voltage change rate and feedback electric current that received, can change and the external electrical network same frequency electric energy that stores into synchronous quasi-sine-wave electric current through active inverter.Its control precision height, adaptivity is good, stable work in work.3, adopt the feedback electric current of anti-phase adder circuit adjustment control AC network and the variation of direct voltage, the ac grid voltage fluctuation is little to electric weight feedback influence, has stopped refusing feedback, postponing feedback or mistake feedback phenomenon, feedback electric weight height of electric energy substantially.4, circuit is simple, and the electric energy conversion is reliable, and energy-saving effect is obvious, does not have harmonic content substantially, and is pollution-free to electrical network, is suitable for as crane, and direct current energies such as various frequency conversion and speed regulation of AC motor brakings such as elevator or storage battery are to the feedback of AC network.
Description of drawings
Fig. 1 is a structured flowchart of the present utility model
Fig. 2 is a main circuit schematic diagram of the present utility model
Fig. 3 is the structural principle block diagram of voltage control loop 5 among Fig. 1
Fig. 4 is the circuit theory diagrams of current detection circuit 6 among Fig. 3
Fig. 5 is the structured flowchart that relates to dc voltage control circuit 8 circuit such as grade among Fig. 3
Embodiment
Below in conjunction with description of drawings and embodiment the utility model is described in further detail:
Referring to Fig. 1, Fig. 2, the utility model is realized the transformation of electrical energy logical process as shown in Figure 1, external dc power U
PNBe connected with the input of capacitive storage circuit 2 with active inverter 3 through isolating diode loop 1, the output of active inverter 3 is connected with AC network through LC filter 4.External dc power U
PNProvide electric energy to charge to capacitive storage circuit 2 through isolating diode loop 1, the electric energy that stores in the capacitive storage circuit 2 changes into and the external electrical network same frequency through active inverter 3, synchronous quasi-sine-wave electric current, after give the external communication electrical network behind the higher harmonic current beyond the LC filter 4 filtering first-harmonics, realized changing the DC power supply energy into the alternating current energy and fed back to the purpose of three-phase alternating current electrical network.Wherein active inverter 3 can adopt three-phase bridge Controllable Active inverter, and its control end is connected with voltage control loop 5.Under the controlling and driving of voltage control loop 5, active inverter 3 can change the DC power supply electric energy into electrical network same frequency, synchronous three-phase alternating current and feeds back to AC network.
Its main circuit of the utility model as shown in Figure 2, external dc power U
PNCan be the voltage of storage capacitor in the voltage frequency converter DC loop, also can be battery tension.U
PNThrough isolating diode D1, D2 capacitor C 1, the C2 charging to polyphone, isolating diode D1, D2 can prevent that the voltage U d on capacitor C 1, the C2 is in outside direct voltage U
PNThe time to the transmission of electricity of outside reversal of power, cause voltage U d short circuit to damage other components and parts in the main circuit in the time of also can preventing external power source P, N terminal shortcircuit, cause external dc power U in the time of can also preventing P, the N end reversal connection of external power source
PNForm the components and parts that big short circuit current is damaged main circuit with voltage U d polyphone.DC power supply U externally
PNUnder capacitor C 1, C2 both end voltage Ud condition, the external power source electric energy charges to capacitor C 1, C2 by isolating diode D1, D2, the interim on the one hand deposit DC power supply of capacitor C 1, C2 electric energy can prevent to produce when power electronic device T1 in the main circuit~T6 from turn-offing overvoltage on the other hand.Under the driving of voltage control circuit 5, six power electronic device T1~T6 in the main circuit three-phase Controllable Active inverter are switch in turn successively, and direct current energy is changed into and outside three phase network same frequency, synchronous AC energy.Power electronic device T1~T6 is the controllable type power electronic device, and they can be IGBT, also can be high power transistor BJT or high-power FET Power MOSFET.The diode that is connected in parallel on power electronic device T1~T6 provides power electronic device T1~afterflow path of electric current when the T6 pipe turn-offs, prevent that inductive current changes the components and parts that produce in the too high voltages damage main circuit suddenly in the circuit, contain a small amount of higher harmonic current in the AC energy of conversion, the LC filter circuit that process inductance L 1~L3 and capacitor C 3~C5 form can weaken the harmonic current content in the AC energy, makes the AC energy that feeds back to the three-phase alternating current electrical network not have harmonic content substantially.
Referring to Fig. 3, Fig. 4, Fig. 5, voltage control loop 5 is by current control circuit 6 in the utility model, alternating voltage control circuit 7, dc voltage control circuit 8, voltage adaptive control circuit 9 and isolated drive circuit 10 are formed, the signal input part of voltage adaptive control circuit 9 respectively with current control circuit 6, alternating voltage control circuit 7, dc voltage control circuit 8 connects, and the output of voltage adaptive control circuit 9 is connected with the input of isolated drive circuit 10, and the output of isolated drive circuit 10 is connected with the control end of three-phase controllable type active inverter.
Current control circuit 6 will be finished real-time detection and the control to three-phase feedback electric current, can adopt as the circuit among Fig. 4 and realize.Current sample device L4, the L5 that two magnetic in the current control circuit 6 are isolated or light is isolated is connected with two-phase power supply on the AC network respectively, have the input of an anti-phase adder A1 in parallel with the signal output part of current sample device L4, L5 respectively through resistance R 1, R2, the output of current sample device L4, L5 and anti-phase adder A1 all inserts voltage adaptive control circuit 9.The current sample device L4, the L5 that isolate with 2 magnetic isolation (as zero magnetoelectricity flow sensor) or light detect U, V two-phase feedback current i
U, i
V, again according to i
U+ i
V+ i
W=0 condition obtains with anti-phase adder A1 and W phase feedback current i
WThis method can save a current sampling circuit and the null condition of three-phase current sum is satisfied in the three-phase current strictness.Current control circuit 6 will be given voltage adaptive control circuit 9 through the current signal after the regulation and control and handle.
Ac grid voltage testing circuit 7 is transformed into synchronous square wave synchronizing signal with three-phase alternating voltage and gives voltage adaptive control circuit 9.Can guarantee the strict same-phase of three-phase feedback electric current and ac grid voltage thus, and can judge whether the AC network side has the fault of the phase failure and misphase.Give voltage adaptive control circuit 9 after the ac grid voltage U that detects in the ac grid voltage testing circuit 7~process rectifier bridge D3 becomes direct voltage simultaneously.
One anti-phase adder A2 is arranged in the dc voltage control circuit 8, and the input of anti-phase adder A2 is in parallel with the end of DC power supply Ud through capacitor C 6, and the two ends of DC power supply Ud and the output of anti-phase adder A2 insert voltage adaptive control circuit 9.Dc voltage control circuit 8 detects the size of direct voltage Ud in the main circuit on the one hand, simultaneously also by anti-phase adder A2, capacitor C 6, the differential circuit that resistance R 4 constitutes is controlled the rate of change of direct voltage Ud, and gives voltage adaptive control circuit 9 with its control signal.
The input of voltage adaptive control circuit 9 is connected with two-phase power supply on the AC network through rectifier bridge D3.Voltage adaptive control circuit 9 receives alternating voltage, direct voltage, information such as DC voltage change rate and feedback electric current, phase place according to ac grid voltage, DC power supply voltage must be greater than the ac grid voltage maximum and by the determined feedback current signal of DC voltage change rate, by the isolated drive circuit 10 that can form by devices such as photoelectronic couplers, change its light current control signal into the forceful electric power actuating signal, thereby the switch motion of 6 last control ends of power electronic device T1~T6 constantly in the decision main circuit, make DC power supply energy efficient rate, low harmonic content, in good time, feed back to AC network reliably.Through elevator lifting braking test, the utility model can economize on electricity more than 20%.