CN103023117A - Electric vehicle charging system with high power quality - Google Patents

Abstract

The invention discloses an electric vehicle charging system with high power quality. A direct-current charger of the electric vehicle charging system is an electric vehicle charger on the basis of a voltage type PWM (pulse width modulation) rectifier, and a control system of the PWM rectifier is of a double-closed-loop control structure with a traditional outer PI (proportion integration) regulating voltage loop and an inner dead-beat control current loop. Harmonic current which is injected into a power grid by the electric vehicle charging system is reduced, and the power quality of the power grid is improved. Besides, an inverter link is added to the electric vehicle charging system, so that the electric vehicle charging system can be connected with a battery pack to charge the battery pack or can be connected with an air conditioning load for electric discharge according to load change conditions (namely a peak period, a valley period and the like) of the power grid, energy can flow in positive and negative directions, the electric vehicle charging system can run in a rectification state to receive the energy from a power-grid side, can also run in an inversion state to transmit the energy to the load, and runs in an approximate unity power factor state, and the utilization efficiency of power resources is improved.

Description

High quality of power supply charging system for electric automobile

Technical field

The invention belongs to the electrical power distribution system field, relate in particular to a kind of high quality of power supply charging system for electric automobile.

Background technology

Ended for the end of the year 2011, Southern Power Grid Company in Guangzhou, Shenzhen, Zhuhai, Zhong Shan, Nanning, Liuzhou, Guilin, Kunming, Haikou, Zhaoqing builds together into 15 and fills electrical changing station, 2953 charging piles, accumulative total is filled and is changed electric number of times approximately 4.9 ten thousand times, fills and changes approximately 2,440,000 kilowatt hours of power consumption.At present, during horse-racing ground, Guangzhou, science town's electric automobile charging station inTouch Lab project are being built as scheduled, for promoting the use of of electric automobile played good demonstration, guiding, service function; And State Grid Corporation of China has built together into 111 electric vehicle charging electrical changing stations, 8930 chargers, and 7245 alternating-current charging piles cover 26 provinces and cities in state's net scope.2008 Beijing Olympic Games electric automobile adopts the battery altering mode to carry out the electric energy supply, adopts altogether 2 fast quick change electric machine people, and 30 groups of reserve batteries can satisfy the electric demand of changing of 50-100 electric bus.Shanghai World's Fair in 2010 is runed 120 pure electric bus altogether, and supporting electrical changing station has 8 fast quick change electric machine people, 112 groups of reserve batteries; On March 15th, 2012, the Gao Antun electric vehicle charging electrical changing station that is positioned at Chaoyang District Beijing Gao Antun circular economy industrial garden formally puts into operation, this station is the strongest electric vehicle charging electrical changing station of largest, service ability in the world, indicates that State Grid Corporation of China's intelligence is filled to change electric construction of service network and be attended by the most momentous results.Wherein, the performance of charging electric vehicle facility becomes one of key element that ev industry makes smooth advances, and it has not only determined stability, charging times, the life-span length of accumulator of electric car, also directly have influence on the user drive experience.

Yet at present the electric automobile dc charging motor of operation is comprised of Technics of Power Electronic Conversion circuit etc., cause harmonic wave to produce and power factor lower, affect the quality of power supply of electrical network.Therefore, need to drop into reactive power compensator and filter being used in conjunction with, thereby strengthened floor space, and increased extra fund input.In addition, be full of the batteries of electric automobile bag discharge of electricity, discharged by the discharge resistance load, can not effectively utilize electric energy.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of high quality of power supply charging system for electric automobile, to reduce charging system for electric automobile to harmonic current content and the reactive power of electrical network, improve the electrical network quality of power supply, in addition, can also realize flowing of the positive and negative both direction of energy, namely may operate at rectification state, from the grid side conveying capacity, also may operate at inverter mode, to the load conveying capacity, make system near the unity power factor operation, improve the utilization ratio of electric power resource.

For solving the problems of the technologies described above, the present invention institute is by the following technical solutions: high quality of power supply charging system for electric automobile, mainly formed by electrokinetic cell bag cabinet, air-conditioning load, charging rack, charge-discharge monitoring system, backstage main website, residual current circuit breaker etc., electrokinetic cell bag cabinet comprises battery management system (BMS) and high tension apparatus unit, batteries of electric automobile bag, direct-current charging interface, and the charging rack comprises charging monitoring unit, dc charging motor, interchange input and protected location, electric power meter, inverter; Electrokinetic cell bag cabinet connects charge-discharge monitoring system by cable, battery management system (hereinafter to be referred as BMS) turns Ethernet access PC by CAN to be realized the battery Real Time Monitoring, and communication channel is set up by Ethernet access backstage main station system and main website in the charging monitoring unit; The inverter of charging rack connects residual current circuit breaker and connects the air-conditioning load again, is used for to the batteries of electric automobile bag discharge that is full of electricity and to the air-conditioning load supplying; The charging rack is from the power taking of three-phase and four-line electrical network, and dc charging motor is transformed to direct current with alternating current, is the charging of batteries of electric automobile bag; The panel of charging rack mainly comprises operating state indicating member, touch-screen, card slot, scram button, charging master control borad, accessory power supply etc.; Dc charging motor adopts the electric automobile battery charger based on voltage type PWM rectifier, comprises three-phase inverter and high frequency DC/DC converter; Three-phase inverter is general voltage source inverter, by 3 switch arms totally 6 power switchs form, its AC is incorporated into the power networks by three pole reactor, DC side connects the next stage circuit by electric capacity; High frequency DC/DC converter is made of single-phase full-bridge inverter, high-frequency coupling transformer and low pressure full-wave rectifier, and single-phase full-bridge inverter is voltage source inverter, by 2 brachium pontis totally 4 power switch pipes form; The control system of PWM rectifier adopts two closed loop controlling structures of traditional PI regulation voltage outer shroud and dead beat control current inner loop; In addition, system increases the inverter link can be connected and charge according to the load variations situation (being the periods such as peak, low ebb) of electrical network system with power brick, perhaps be connected with the air-conditioning load and discharge, realize that flowing of the positive and negative both direction of energy (namely may operate at rectification state, from the grid side conveying capacity, also may operate at inverter mode, to the load conveying capacity, make system near the unity power factor operation, improve the utilization ratio of electric power resource).

Communication channel is uploaded to the charging monitoring unit by 485 communication buss with output voltage and electric current, module protection and the warning information of dc charging motor module; The control command that the charging monitoring unit issues is also accepted and carry out to dc charging motor by 485 communication buss.

The charging rack uses CAN to be connected with the batteries of electric automobile cabinet with the monitor terminal of battery management system (BMS) information interaction of electric automobile and communicates, and monitoring battery case operating state is obtained the power battery charging parameter to guarantee charging safety; Obtain battery charging demand parameter, and adjust in real time charge parameter; Obtain rechargeable battery state in the charging process; Obtain the work state information of single battery; Receive the request of BMS terminal charge; Obtain the charge information of BMS statistics; The data such as the charging voltage of the whole bag of monitoring electrokinetic cell bag, charging current, ceiling voltage, minimum voltage, the maximum temperature of monitoring cell, monitoring charging SOC etc.

For existing charging system for electric automobile produce harmonic wave, the problem such as power factor is lower, utilization rate of electrical is low, the inventor has designed the high quality of power supply charging system for electric automobile of the present invention, the dc charging motor of this system adopts the electric automobile battery charger based on voltage type PWM rectifier, and the control system of PWM rectifier adopts two closed loop controlling structures of traditional PI regulation voltage outer shroud and dead beat control current inner loop.Therefore, this system can be connected with power brick and charge according to the load variations situation (being the periods such as peak, low ebb) of electrical network, perhaps be connected with the air-conditioning load and discharge, realize flowing of the positive and negative both direction of energy, namely may operate at rectification state, from the grid side conveying capacity, also may operate at inverter mode, to the load conveying capacity, make system near the unity power factor operation, improve the utilization ratio of electric power resource.In addition, use the present invention and also can reduce charging system for electric automobile to harmonic current content and the reactive power of electrical network, improve the electrical network quality of power supply.

Description of drawings

Fig. 1 is the structured flowchart of the high quality of power supply charging system for electric automobile of the present invention.

Fig. 2 is the fundamental diagram of charger module in the high quality of power supply charging system for electric automobile of the present invention.

Fig. 3 is the output characteristics figure of rectification module in the high quality of power supply charging system for electric automobile of the present invention, and curve and I axle intersection point represent output short-circuit among the figure.

Fig. 4 is the electric illustraton of model of single-phase equivalence of voltage-type rectifier.

Fig. 5 is PWM rectifier dead beat control structure figure.

Fig. 6 is based on the structure chart of the electric automobile battery charger of voltage source inverter.

Embodiment

Fig. 1 has shown the high quality of power supply charging system for electric automobile of the present invention, mainly formed by electrokinetic cell bag cabinet, air-conditioning load, charging rack, charge-discharge monitoring system, backstage main website, residual current circuit breaker etc., electrokinetic cell bag cabinet comprises battery management system (BMS) and high tension apparatus unit, batteries of electric automobile bag, direct-current charging interface, and the charging rack comprises charging monitoring unit, dc charging motor, interchange input and protected location, electric power meter, inverter; Electrokinetic cell bag cabinet connects charge-discharge monitoring system by cable, and battery management system (BMS) turns Ethernet access PC by CAN to be realized the battery Real Time Monitoring, and communication channel is set up by Ethernet access backstage main station system and main website in the charging monitoring unit; The inverter of charging rack connects residual current circuit breaker and connects the air-conditioning load again, is used for to the batteries of electric automobile bag discharge that is full of electricity and to the air-conditioning load supplying; The charging rack is from the power taking of three-phase and four-line electrical network, and dc charging motor is transformed to direct current with alternating current, and dc charging motor again connecting electric automobile power brick is the charging of batteries of electric automobile bag; The panel of charging rack mainly comprises operating state indicating member, touch-screen, card slot, scram button, charging master control borad, accessory power supply etc.; Dc charging motor adopts the electric automobile battery charger based on voltage type PWM rectifier.

Communication channel is uploaded to the charging monitoring unit by 485 communication buss with dc charging motor module output voltage and electric current, module protection and warning information, and the control command that the charging monitoring unit issues is also accepted and carry out to dc charging motor by 485 communication buss.

This charging system has the telecommunication passage, can communicate with the management of charging and discharging main website charging and discharging state of long distance control system charger, electrokinetic cell bag; Can support multiple batteries type of charge, the type of batteries comprises nickel chromium triangle, ni-mh, plumbic acid, lithium ion battery; Have constant voltage, constant current, floating charge, trickle intelligent charging function; The system monitoring unit can be controlled charger and automatically carry out constant current voltage limiting charging → constant voltage charge → trickle charge → stop charge operation state; Have the kinds of protect mode, comprise input overvoltage/under-voltage, output overvoltage, overcurrent, excess temperature, overload, short-circuit protection etc.; Possess the function that charging voltage/electric current charges is set as required, guarantee that storage battery does not overcharge, do not owe to fill; Discharging current answers constant current adjustable, and input and output have automatic protection functions; Have automatic and manual powered pattern, the automatic charging pattern is dynamically adjusted charge parameter according to state and the load characteristic of storage battery, carries out stage by stage intelligent charge; Manual powered pattern is that the parameters such as charging modes, charging voltage, charging current are set by operating personnel, carries out corresponding operating, finishes charging process.Whole operating process has clear and definite operation indication information; Has the demonstration output function.The parameter that shows output comprises charging voltage, charging current, charge power, charging interval, charged electrical energy and charge information; In manual powered pattern, show the artificial input information; Corresponding information is arranged when breaking down; Other relevant informations of energy display monitoring unit output; Can easily input web-privilege password Web; Can keep the record space that is no less than 50,000 transaction data; Have time adjustment function, satisfy the PPS(pulse per second (PPS)), PPM(divides pulse) to the time requirement, and to time error less than 1ms; Have voltage stabilizing and flow stabilizing function, namely when changing in the excursion of stipulating in line voltage or the load characteristic technical protocol, the voltage stabilization and current stabilization deviation of normal operation is no more than 1%; Have function of safety protection: input side overvoltage protection, input side under-voltage protection, output overcurrent protection, anti-output short-circuit, overload and overheat protective function, and possess scram button; Have soft start function, soft-start time is 3-8S, and inrush current is not more than 110% of rated current; Have overload capacity: the charger power supply has the ability of the continuously operation of 100% load, 1 minute overlond running of 150% load.

Batteries has battery management system, and batteries is automatically managed and protected Real-Time Monitoring battery-operated state and parameters.Power brick is comprised of battery rack, battery case, ferric phosphate lithium cell, BMS, high tension apparatus, remote monitoring module, copper bar and associated cable.Use 50Ah LiFePO4 battery core totally 1 and 125 strings, total capacity 50Ah, total voltage 400V.A battery rack is arranged in the power brick, and battery rack divides 4 layers, wherein places 13 battery cases for the 1st ~ 3 layer, places BMS and high tension apparatus for the 4th layer.In 13 battery cases, 12 every casees fill 10 economize on electricity cores, and the 13rd battery case fills 5 economize on electricity cores, and the battery case loam cake uses bakelite plate to protect.A whole set of battery system is comprised of 125 crosstalk ponds, and each crosstalk pond module voltage, total voltage, total current, both positive and negative polarity insulation resistance, the battery case temperature of battery pack detected, and when different situation appears in battery, can communicate warning.

As shown in Figure 2, charger module output has 485 and the CAN communication interface, and convenient access automated system communicates, and is furnished with 485 communication interfaces.Air blast cooling, mechanical shock and antidetonation grade satisfy industry requirement, environmental protection.The built-in over-voltage protective circuit, overvoltage appears and after module be automatically locked, module fault indicator is bright; Over-voltage protection point: 490V ± 10V; The output current limiting protection: module output current maximum constraints is 1.05 times of output-current ratings (being 14A); Overheat protector: the module heat dissipating actuator temperature is that 85-95 ℃ of time limit power is to specified 40%-60%; Temperature shutdown above 95 ℃ recovers output when temperature is reduced to 75 ℃; Short-circuit protection: adopt the sagging current-limiting mode of retraction, the blocks current output characteristic is seen Fig. 3, and module is pulled down to zero to output voltage in moment during output short-circuit, and limiting short-circuit current is at below 15% of output-current rating.But the module long-term work can not damage in short-circuit condition, and the rear module of fixing a breakdown can be resumed work automatically.Short-circuit protection is not taked the locked mode of shutting down, and is conducive to the battery charging.

Fig. 4 has shown the single-phase equivalent electrical model of PWM rectifier, supposes line voltage u _S=U _SSin ω t, rectifier output voltage u _N=U _NSin (ω t-θ), wherein θ is u _SAnd u _NPhase angle difference; ω is the first-harmonic angular frequency.Circuit relationships according to Fig. 4 has:

$L\frac{{\mathrm{di}}_C}{\mathrm{dt}}=u_S-u_N---\left(1\right)$

So, fundamental current is:

$i_C=\frac{1}{\mathrm{\ωL}}[U_N\cos (\mathrm{\ωt}-\mathrm{\θ})-U_S\cos \mathrm{\ωt}]---\left(2\right)$

The fundamental active power of electric network source output then And reactive power

Be respectively:

${\stackrel{\‾}{P}}_1=\frac{{\∫}_0^{T_1}{U}_S{i}_C\sin \mathrm{\ωtdt}}{T_1}=\frac{U_S{U}_N\sin \mathrm{\θ}}{2\mathrm{\ωL}}---\left(3\right)$

${\stackrel{\‾}{Q}}_1=\frac{{\∫}_0^{T_1}{U}_S{i}_C\cos \mathrm{\ωtdt}}{T_1}=\frac{[U_S{U}_N\cos \mathrm{\θ}-U_S^2]}{2\mathrm{\ωL}}---\left(4\right)$

Wherein, T ₁It is the primitive period.

Therefore, three-phase fundamental active power

And reactive power

Be respectively:

${\stackrel{\‾}{P}}_{31}={3\stackrel{\‾}{P}}_1=\frac{{3U}_S{U}_N\sin \mathrm{\θ}}{2\mathrm{\ωL}}---\left(5\right)$

${\stackrel{\‾}{Q}}_{31}=3{\stackrel{\‾}{Q}}_1=\frac{3[U_S{U}_N\cos \mathrm{\θ}-U_S^2]}{2\mathrm{\ωL}}---\left(6\right)$

By formula (5) as can be known, as 0 °＜θ ₁In the time of＜180 °,

Be that three-phase rectifier absorption power grid energy charges to dc bus capacitor, can realize that then power grid energy is to the transfer of dc bus capacitor; As-180 °＜θ ₁In the time of＜0 °,

Being energy is transmitted to AC by the DC side of three-phase rectifier, and the dc bus capacitor discharge can realize that then the dc bus capacitor energy is to the transfer of electrical network.So just can realize the four-quadrant PWM rectification operation of three-phase rectifier, simultaneously, from (6) as can be known, by the output voltage of reasonable control three-phase rectifier, rectifier can send or absorb to electrical network the reactive current of correspondence.

As shown in Figure 5, the control system of PWM rectifier adopts two closed loop controlling structures of traditional PI regulation voltage outer shroud and dead beat control current inner loop to guarantee the rapidity of Systems balanth and response, making system can (be the peak according to the load variations situation of electrical network, the periods such as low ebb) be connected with power brick and charge, perhaps be connected with the air-conditioning load and discharge, realize that flowing of the positive and negative both direction of energy (namely may operate at rectification state, from the grid side conveying capacity, also may operate at inverter mode, to the load conveying capacity, make system near the unity power factor operation, improve the utilization ratio of electric power resource).According to the dead beat control principle, dead beat control voltage instruction computing formula is under the dq coordinate system:

$\left\{\begin{array}{c}{u}_d\left(k\right)=-\frac{L}{T}{i}_d^{*}(k+1)+\frac{L-\mathrm{RT}}{T}{i}_d\left(k\right)+{\mathrm{\ωLi}}_q\left(k\right)+e_d\left(k\right)\\ u_q\left(k\right)=-\frac{L}{T}{i}_q^{*}(k+1)+\frac{L-\mathrm{RT}}{T}{i}_q\left(k\right)+{\mathrm{\ωLi}}_d\left(k\right)+e_q\left(k\right)\end{array}\right.---\left(7\right)$

Wherein, $i_d^{*}\left(t\right),i_q^{*}\left(t\right)$ DC quantity behind system stability, and $i_d^{*}(k+1)=i_d^{*}\left(k\right),$ $i_q^{*}(k+1)=i_q^{*}\left(k\right).$

As shown in Figure 6, the electric automobile battery charger based on voltage type PWM rectifier comprises three-phase inverter and high frequency DC/DC converter; Three-phase inverter is general voltage source inverter, by 3 switch arms totally 6 power switchs form, its AC is incorporated into the power networks by three pole reactor L, DC side is passed through capacitor C _dConnect the next stage circuit.In Fig. 6, high frequency DC/DC converter is made of single-phase full-bridge inverter, high-frequency coupling transformer and low pressure full-wave rectifier, and wherein, single-phase full-bridge inverter is voltage source inverter, by 2 brachium pontis totally 4 power switch pipes form.The PWM rectifier of energy capable of bidirectional flowing not only embodies AC/DC unsteady flow characteristic (rectification), but also shows DC/AC unsteady flow characteristic (active inversion), thereby is a kind of reversible PWM current transformer.PWM rectifier main circuit develops into full-control type device bridge circuit of today from early stage half control type device bridge circuit, and the control of PWM switch develops into soft switch modulation by simple hard switching modulation, uses industrial all successfully the input.By adopting the PWM commutation technique to realize the High Power Factor rectification of system, reduce the idle and harmonic current content of system, improve the quality of power supply of electrical network.

The charging rack uses CAN to be connected with the batteries of electric automobile cabinet with the monitor terminal of BMS information interaction and communicates, and monitoring battery case operating state is obtained the power battery charging parameter to guarantee charging safety; Obtain battery charging demand parameter, and adjust in real time charge parameter; Obtain rechargeable battery state in the charging process; Obtain the work state information of single battery; Receive the request of BMS terminal charge; Obtain the charge information of BMS statistics; The data such as the charging voltage of the whole bag of monitoring electrokinetic cell bag, charging current, ceiling voltage, minimum voltage, the maximum temperature of monitoring cell, monitoring charging SOC etc.

Claims (3)

1. one kind high quality of power supply charging system for electric automobile, it is characterized in that mainly being formed by electrokinetic cell bag cabinet, air-conditioning load, charging rack, charge-discharge monitoring system, backstage main website, residual current circuit breaker, electrokinetic cell bag cabinet comprises battery management system BMS and high tension apparatus unit, batteries of electric automobile bag, direct-current charging interface, and the charging rack comprises charging monitoring unit, dc charging motor, interchange input and protected location, electric power meter, inverter; Described electrokinetic cell bag cabinet connects charge-discharge monitoring system by cable, and battery management system turns Ethernet access PC by CAN to be realized the battery Real Time Monitoring, and communication channel is set up by Ethernet access backstage main station system and main website in the charging monitoring unit; The inverter of described charging rack connects residual current circuit breaker and connects the air-conditioning load again, is used for to the batteries of electric automobile bag discharge that is full of electricity and to the air-conditioning load supplying; The charging rack is from the power taking of three-phase and four-line electrical network, and it is the charging of batteries of electric automobile bag that dc charging motor is transformed to direct current with alternating current; The panel of charging rack mainly comprises operating state indicating member, touch-screen, card slot, scram button, charging master control borad, accessory power supply; Described dc charging motor adopts the electric automobile battery charger based on voltage type PWM rectifier, comprises three-phase inverter and high frequency DC/DC converter; Described three-phase inverter is voltage source inverter, by 3 switch arms totally 6 power switchs form, its AC is incorporated into the power networks by three pole reactor, DC side connects the next stage circuit by electric capacity; Described high frequency DC/DC converter is made of single-phase full-bridge inverter, high-frequency coupling transformer and low pressure full-wave rectifier, and single-phase full-bridge inverter is voltage source inverter, by 2 brachium pontis totally 4 power switch pipes form; The control system of described PWM rectifier adopts two closed loop controlling structures of traditional PI regulation voltage outer shroud and dead beat control current inner loop; In addition, system increases the inverter link can be connected according to the load variations situation of electrical network system to charge, perhaps be connected with the air-conditioning load and discharge with power brick, the positive and negative both direction of realization energy mobile.

2. high quality of power supply charging system for electric automobile according to claim 1 is characterized in that: described communication channel is uploaded to the charging monitoring unit by 485 communication buss with output voltage and electric current, module protection and the warning information of dc charging motor module; The control command that the charging monitoring unit issues is also accepted and carry out to dc charging motor by 485 communication buss.

3. high quality of power supply charging system for electric automobile according to claim 1, it is characterized in that: described charging rack uses CAN to be connected with the batteries of electric automobile cabinet with the monitor terminal of BMS information interaction and communicates, monitoring battery case operating state is obtained the power battery charging parameter to guarantee charging safety; Obtain battery charging demand parameter, and adjust in real time charge parameter; Obtain rechargeable battery state in the charging process; Obtain the work state information of single battery; Receive the request of BMS terminal charge; Obtain the charge information of BMS statistics; Charging voltage, the charging current data of the whole bag of monitoring electrokinetic cell bag, ceiling voltage, minimum voltage, the maximum temperature of monitoring cell, monitoring charging SOC.

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