Summary of the invention
The object of the present invention is to provide one kind, and efficient PFC electricity can be all kept in full-load range
Road and the AC charger for electric vehicle for applying it.
In order to achieve the above objectives, the technical solution adopted by the present invention is that:
A kind of circuit of power factor correction, applied in the AC/DC converter of AC charger for electric vehicle, the AC/DC
Converter includes AC/DC translation circuit, and the input terminal of the circuit of power factor correction is connected with the AC/DC translation circuit
It connects, the output end of the circuit of power factor correction forms the output end of the AC/DC converter and connects load, and feature exists
In: the circuit of power factor correction includes:
Two groups of Boost circuits, Boost circuit described in two groups is in parallel, and the input terminal of the Boost circuit and the AC/DC are converted
Circuit is connected, and the output end of the Boost circuit connects the load, and the Boost circuit includes inductance, master control pipe and storage
Flow tube, the master control pipe in Boost circuit described in two groups are based on corresponding control signal and turn on and off, two groups of institutes of realization
State Boost circuit alternation;
Control circuit, the control circuit export corresponding different works according to the size of the bearing power P of the AC/DC converter
The control signal of operation mode give two groups respectively described in Boost circuit master control pipe;
The operating mode includes determining frequency mode, variable mode and frequency-hopping mode;
When the load boundary value of bearing power P >=first of the AC/DC converter, frequency mode is determined using described, described in two groups
The received control signal of Boost circuit determines frequency PWM letter using the maximum frequency set for control circuit output
Number;When the load boundary value of bearing power P >=second of the AC/DC converter described in the first load boundary value >, using the change
Frequency mode, the received control signal of Boost circuit described in two groups are according to corresponding inductive current for the control circuit
The no frequency conversion pwm signal for reaching reference amplitude and exporting;When bearing power P the second load boundary of < of the AC/DC converter
When value, using the frequency-hopping mode, the received control signal of Boost circuit described in two groups is the control circuit only in institute
The output voltage for stating AC/DC converter drops to a series of pulse signals exported when the voltage threshold of setting;The AC/DC becomes
Full-load power > the first load boundary value > the second load boundary value of parallel operation.
Preferably, the control circuit includes:
For acquiring the output voltage of the AC/DC converter and the output voltage sampling module of output voltage signal;
For being selected according to the bearing power P of the AC/DC converter and the comparison result output associative mode of wherein given threshold
Select the multi-threshold comparing unit of signal;
For according to presently described mode select signal or according to presently described mode select signal and acquiring the inductance electricity
Flow the signal output module of the corresponding control signal of the current signal/voltage signal output obtained;
The input terminal of the output voltage sampling module is connected with the output end of the Boost circuit, and the multi-threshold compares
The input terminal of unit is connected with the output end of the sampling module, the input terminal of the signal output module respectively with it is described more
Threshold value comparison unit, the Boost circuit, the output voltage sampling module are connected, the output of the signal output module
End is connected with the master control pipe of Boost circuit described in two groups respectively.
Preferably, the signal output module includes corresponding for the master control pipe in Boost circuit described in generating one group
The PWM comparator for determining frequency pwm signal or the frequency conversion pwm signal, delay circuit are used for the electricity of Boost described in one group of generation
A series of Ton generator of the corresponding pulse signals of master control pipe in road, the input terminal of the PWM comparator point with it is described
Boost circuit, the voltage sample module are connected and input the input voltage of the Boost circuit and the product of output voltage
Signal, the current signal, the master control pipe open signal obtained according to the current signal, the output voltage signal is via institute
It states the first switch of mode select signal control and accesses the PWM comparator, the master control pipe open signal is via the mould
The second switch of formula selection signal control and access the PWM comparator, the output end of the PWM comparator is divided into two-way, one
Road access one group described in Boost circuit, access another group after the delayed circuit of another way described in Boost circuit;The Ton occurs
The input terminal of device is connected with the multi-threshold comparing unit, and output end is connected to the output end of the PWM comparator.
Preferably, the signal output module further includes for acquiring the inductive current and exporting the current signal
Current sampling circuit, for judging master control pipe opening state in the Boost circuit and exporting the master control pipe open signal
Zero cross detection circuit, the input voltage for realizing the Boost circuit are multiplied with output voltage to be calculated and exports the product
The multiplier of signal, the input terminal of the current sampling circuit are connected with the Boost circuit, the current sampling circuit
Output end is connected with the input terminal all the way of the PWM comparator all the way, the input terminal of the zero cross detection circuit and the electricity
Stream sample circuit another output end be connected, the output end of the zero cross detection circuit through the second switch and with it is described
The another way input terminal of PWM comparator is connected, the input terminal all the way and the input terminal phase of the Boost circuit of the multiplier
Connection, the output end of the output voltage sampling module are connected through the first switch with another input terminal of the multiplier
It connects, the output end of the multiplier is connected with another input terminal of the PWM comparator.
Preferably, the current sampling circuit is connected with Boost circuit described in one group.
Preferably, the current sampling circuit is connected with the source electrode of master control pipe described in Boost circuit described in one group.
Preferably, the master control pipe be silicon substrate MOSFET, silicon carbide MOSFET, the gallium nitride MOSFET based on silicon base,
Gallium nitride MOSFET or GaAs MOSFET.
Preferably, the storage flow tube is fast recovery diode, Ultrafast recovery diode or silicon carbide diode.
Preferably, the variable mode correspondence is preset with low-limit frequency, and the frequency of the frequency conversion pwm signal is greater than or equal to
The low-limit frequency.
A kind of AC charger for electric vehicle, it is described including the AC/DC converter with power factor emendation function
The circuit of power factor correction that AC/DC converter includes AC/DC translation circuit, is connected with the AC/DC converter, the function
Rate factor correcting circuit uses circuit of power factor correction above-mentioned.
Due to the above technical solutions, the present invention has the following advantages over the prior art: the present invention uses multimode
Formula control strategy, in such a way that different control strategies are taken in different loads section, so that the power factor of AC charger
Adjusting level all keeps high efficiency in full-load range.
Embodiment one: AC charger for electric vehicle, including with power factor emendation function AC/DC converter and
DC/DC converter with electrical isolation and buck functionality.As shown in Fig. 1, AC/DC converter includes AC/DC transformation electricity again
Road and circuit of power factor correction.
AC/DC translation circuit includes the bridge conversion circuit that four diodes are constituted, and input terminal is AC/DC converter
Input terminal and input exchange signal, and its output end is then connected with the input terminal of circuit of power factor correction, and power because
The output end of number correcting circuit then forms the output end of AC/DC converter and connects load.
Circuit of power factor correction includes two groups of Boost circuits and the control electricity for controlling two groups of Boost circuit work
Road.Two groups of Boost circuits are in parallel and one group of input terminal and one group of output end is collectively formed, the input terminal and AC/DC of Boost circuit
Translation circuit is connected, and the output end of Boost circuit connects load.Every group of Boost circuit includes inductance (two groups of Boost circuits
In inductance be respectively L1, L2), master control pipe (the master control pipe in two groups of Boost circuits is respectively S1, S2) and store (two groups of flow tube
Storage flow tube in Boost circuit is respectively D1, D2), one end of inductance forms an input terminal and is connected to AC/DC transformation electricity
Road, the other end of inductance are divided into two-way, then formed with one end other end that is connected, and stores flow tube for storing flow tube all the way one it is defeated
Outlet, i.e. outlet side positive ends, another way are connected with master control pipe, and the other end of master control pipe then connects earthed circuit reference
Ground.When master control pipe is in the different conditions turned on and off, Boost circuit completes charging and discharging process.Two groups of Boost electricity
Master control pipe in road is based on corresponding control signal and is switched on or off, and realizes that two groups of Boost circuits work alternatively (immediately
The mode that misphase 180 degree works in sequence).From topological structure, the input side of two groups of Boost circuits is in parallel, input voltage one
It causes, input current superposition;The outlet side of two groups of Boost circuits is in parallel, and output voltage is consistent, output electric current superposition.
Usual master control pipe is silicon substrate MOSFET, silicon carbide MOSFET, gallium nitride MOSFET, gallium nitride based on silicon base
MOSFET or GaAs MOSFET.Storage flow tube is fast recovery diode, Ultrafast recovery diode or silicon carbide diode.With
The fast development of device for power switching technology, novel semiconductor material are continuously available application.In order to promote the conversion effect of circuit
Rate increases power density, reduces Electromagnetic Launching, and the MOSFET used in this programme uses silicon based gallium nitride material.Silicon substrate nitridation
Gallium MOSFET substantially drops in the case where the advantages that retaining conventional gallium nitride power device switching frequency high high temperature resistant, radiation hardness
The low requirement to driving circuit, is easy to apply.Power diode uses silicon carbide diode, there's almost no Reverse recovery
Advantage significantly reduces switching loss and radiation interference.
Control circuit is used for the size according to the bearing power P of AC/DC converter and exports corresponding different working modes
Control signal gives the master control pipe of two groups of Boost circuits respectively, to realize the control to work two groups of Boost circuits.Using working as
Preceding output power takes the percentage of load output power to determine the load condition of AC/DC converter, can determine therefrom that several
Load boundary value, such as the first load boundary value and the second load boundary value, and the full-load power > first of AC/DC converter is loaded
Boundary value > the second load boundary value.For the bearing power of AC/DC converter, it is usually classified as full load condition (AC/DC
Present load power=AC/DC converter full-load power of converter), heavy condition (the full-load power > of AC/DC converter
The present load power of AC/DC converter >=the first load boundary value), middle load state/middle low power state (the first load boundary
The present load power of value > AC/DC converter >=the second load boundary value) and light condition (AC/DC converter it is current negative
Carry the second load boundary of power < value), then the above-mentioned different conditions of corresponding A C/DC converter present load power, are respectively adopted
Three kinds of operating modes.Above two determine that the load boundary value of operating mode switching can be according to corresponding with actual loading boundary
Outer voltage output valve determines.Boundary needs to be arranged the stagnant ring of minute widths to prevent frequent switching.
Operating mode includes determining frequency mode (or continuous current mode conduction mode (Continous Conduction
Mode, CCM)), variable mode (or critical current mode conduction mode (Boundary Conduction Mode, BCM))
With frequency-hopping mode (Multi-Cycle Mode, MCM).When bearing power >=first load boundary value of AC/DC converter, i.e.,
When in heavy duty or full load condition, using frequency mode is determined, the received control signal of two groups of Boost circuits is that control circuit is defeated at this time
The maximum frequency using setting out determines frequency pwm signal.When the first load boundary value > AC/DC converter bearing power >=
Second load boundary value, that is, when being in middle load state, using variable mode, the received control signal of two groups of Boost circuits is control
Whether circuit processed reaches reference amplitude according to corresponding inductive current and the frequency conversion pwm signal that exports.When bearing for AC/DC converter
Carry the second load boundary of power < value, that is, when being in light condition, using frequency-hopping mode, two groups of received controls of Boost circuit
Signal is a series of pulses that control circuit is only exported when the output voltage of AC/DC converter drops to the voltage threshold of setting
Signal.
In order to realize the output of above-mentioned various control signals, the scheme of control circuit are as follows: control circuit includes output voltage
Sampling module, multi-threshold comparing unit and signal output module.
Output voltage sampling module is used to acquire the output voltage and output voltage signal of AC/DC converter, input terminal
It is connected with the output end of Boost circuit.Output voltage sampling module includes the partial pressure being connected with the output end of Boost circuit
Circuit and compensation circuit and error amplifier.
The input terminal of multi-threshold comparing unit is connected with the output end of output voltage sampling module, is used for according to AC/
The bearing power P of DC converter and the comparison result of wherein given threshold export associative mode selection signal.I.e. in multi-threshold ratio
Compared with the threshold value for being preset with multiple bearing powers for multilevel iudge AC/DC converter in unit and belonging to any state, then root
According to the output voltage of AC/DC converter, it can determine its present load based on the output voltage of collected Boost circuit
State, to export the corresponding mode select signal of operating mode for needing to use.
The input terminal of signal output module respectively with multi-threshold comparing unit, Boost circuit, output voltage sampling module phase
Connection, the output end of signal output module are connected with the master control pipe of two groups of Boost circuits respectively.Signal output module is for defeated
Corresponding control signal gives two groups of Boost circuits out, is to export control signal according to present mode selection signal, either
Corresponding control signal is exported according to current signal/voltage signal that present mode selection signal and acquisition inductive current obtain
's.Specifically, signal output module mainly includes PWM comparator, Ton generator, delay circuit, wherein PWM comparator and Ton
Generator is for output to control signal under different working modes respectively.The input terminal of PWM comparator point and Boost circuit,
Voltage sample module is connected, thus input the input voltage of Boost circuit and the product signal of output voltage, current signal,
The master control pipe open signal obtained according to current signal.Wherein, output voltage signal controlled via mode select signal first
It switchs and accesses PWM comparator, master control pipe open signal accesses PWM and compare via the second switch that mode select signal controls
Device.The input terminal of Ton generator is connected with multi-threshold comparing unit.The output end of Ton generator is connected to PWM comparator
Output end and form common output end, the output end of PWM comparator is divided into two-way, accesses one group of Boost circuit all the way, another
Another group of Boost circuit is accessed after the delayed circuit in road.PWM comparator is used to generate the master control pipe pair in one group of Boost circuit
That answers determines frequency pwm signal or frequency conversion pwm signal, and the master control pipe that Ton generator is then used to generate in one group of Boost circuit is corresponding
A series of pulse signals.
In order to cooperate the generation of PWM comparator to determine the demand of frequency pwm signal or frequency conversion pwm signal, the signal output module is also
Including for acquiring inductive current and output current signal current sampling circuit, for judging that master control pipe is opened in Boost circuit
Logical state and the zero cross detection circuit, the input voltage for realizing Boost circuit and output electricity for exporting master control pipe open signal
Pressure, which is multiplied, calculates and exports the multiplier of product signal.The input terminal of current sampling circuit is connected with one group of Boost circuit, can
To be connected with the source electrode of master control pipe in this group of Boost circuit, output end all the way and the PWM comparator of current sampling circuit
Input terminal is connected all the way, and the input terminal of zero cross detection circuit is connected with the another output end of current sampling circuit, zero passage
The output end of detection circuit is connected through second switch and with the another way input terminal of PWM comparator, the input all the way of multiplier
End is connected with the input terminal of Boost circuit, and the output end of output voltage sampling module is another through first switch and multiplier
Input terminal is connected, and the output end of multiplier is connected with another input terminal of PWM comparator.
The microcontroller with high-resolution, high-precision, the ADC module of low delay and PWM module can be used, such as
The 16 position digital signal controller chip dsPIC33EP series or Texas of Microchip Technology Inc company
The TMS320F28 series of Instruments company, carries out voltage, electric current, the acquisition of temperature information and Three models in circuit
Boundary judgement and switching.Meanwhile ring needed for carrying out circuit steady operation itself using such chip and respond transient process
Road control and adjustment.
The working principle of above-mentioned circuit of power factor correction are as follows: through the transformed direct current signal of AC/DC translation circuit in function
In rate factor correcting circuit, by being transferred to load after the Boost circuit of alternation.According to the of different sizes of load, control
Circuit output different working modes corresponding different control signals makes two groups of Boost circuits complete its function, according to circuit
The actual conditions of load, control model are determining frequency mode, variable mode, carry out seamless switching between frequency-hopping mode.When fully loaded or again
When load, multi-threshold comparing unit controls first switch closure, then PWM comparator is based on current state and exports and determine frequency pwm signal,
It is sent into one group of Boost circuit all the way and controls its master control pipe S1, be sent into another group of Boost circuit after the delayed circuit of another way
Its master control pipe S2 is controlled, so that two groups of Boost circuits are worked alternatively according to preset highest frequency, and realizes and determines frequency mode, with
Obtain lesser inductive current ripple and conduction loss.If being equipped with the silicon carbide diode almost without Reverse recovery to optimize out
Loss is closed, efficiency can be improved.When carrying in the middle, multi-threshold comparing unit control first switch and the second switch is closed, used
Zero detection circuit opens the moment judge master control pipe, and master control need to be turned off when inductive current rises to sine wave reference amplitude
Pipe is based on this, and PWM comparator exports frequency conversion pwm signal, makes the two groups of variations of Boost circuit based on its inductive current and changes
Working condition.Sofe Switch may be implemented in this variable mode, greatly reduces switching loss, simultaneously because load and it is little, so
Conduction loss is also relatively small, and the whole efficiency of converter compares optimization.Under the variable mode, due to the switch of circuit work
Frequency is reduced as load reduces, therefore can be for the corresponding default low-limit frequency of variable mode, so that frequency conversion pwm signal
The switching frequency of the master control pipe controlled, which drops to after the low-limit frequency, no longer to be reduced, but is remained unchanged, i.e. whole process
The frequency of middle frequency conversion pwm signal is consistently greater than or is equal to the low-limit frequency.When at light load, control circuit is (main by Ton generator
Keyholed back plate service time generator) exported when the output voltage of AC/DC converter drops to the voltage threshold of setting it is a series of solid
After the pulse signal for determining duty ratio, master control pipe is in an off state always, until the output voltage of AC/DC converter drops to again
A series of pulse signals are exported when the voltage threshold of setting once again.Switching frequency can be greatly lowered in this frequency-hopping mode, show
Write improving light-load efficiency.
The beneficial effect of above-mentioned circuit of power factor correction is: using misphase 180 degree working method in parallel and timing
Two groups of Boost circuits, effectively reduce voltage, the current ripples of input side and outlet side, reduce to filter capacitor capacitance
Requirement, simplify the design of input side electromagnetic interface filter;Two groups of Boost circuits go shares output power, so that converter dissipates
Heat is more uniform.In terms of control model, according to actual loading situation, make converter work in different operating modes.Work as change
When parallel operation is in heavy duty or full load condition, it is allowed to work in and determines frequency mode to obtain lesser inductive current ripple and conducting damage
Consumption.Meanwhile the silicon carbide diode almost without Reverse recovery is equipped with to optimize switching loss, so as to improve efficiency.Work as load
When in middle low power state, judge that supervisor's opens the moment with zero cross detection circuit, when inductive current rises to sine wave
When the amplitude of reference, shutdown supervisor.Sofe Switch may be implemented in this variable mode, greatly reduces switching loss.Simultaneously because negative
It carries and little, so conduction loss is also relatively small, the whole efficiency of converter compares optimization.When converter is in light condition
When, it is main after control system continuously issues the pulse of several fixed duty cycles by Ton generator (supervisor's service time generator)
Pipe is in an off state always, reissues pulse train after output voltage falls to certain threshold value.This frequency-hopping mode
Switching frequency is greatly lowered, light-load efficiency can be obviously improved.The program is made by specific circuit topology and control method
The input voltage and input current same-phase as far as possible of circuit are obtained, and harmonic component contained in input current waveform is few as far as possible.
The above embodiments merely illustrate the technical concept and features of the present invention, and its object is to allow person skilled in the art
Scholar cans understand the content of the present invention and implement it accordingly, and it is not intended to limit the scope of the present invention.It is all according to the present invention
Equivalent change or modification made by Spirit Essence, should be covered by the protection scope of the present invention.