CN103187896A

CN103187896A - Cascading middle-high voltage electric car converter topology and control method of same

Info

Publication number: CN103187896A
Application number: CN2011104573846A
Authority: CN
Inventors: 许烈
Original assignee: BEIJING UNISON ELECTRONICS TECHNOLOGY Co Ltd
Current assignee: BEIJING UNISON ELECTRONICS TECHNOLOGY Co Ltd
Priority date: 2011-12-31
Filing date: 2011-12-31
Publication date: 2013-07-03

Abstract

Volume of a hybrid power vehicle-mounted controller or volume of a purely motor-driven controller improves, the voltage class of series battery sets of the hybrid power vehicle-mounted controller or that of the purely motor-driven controller reaches to 600V-1000V, and the hybrid power vehicle-mounted controller or the purely motor-driven controller are matched with a 380V-690V alternative-current asynchronous motor or a 380V-690V permanent magnet synchronous motor. A two-level structure is adopted and the battery sets are largely connected in series. Voltages of each battery in series circuits differ because of imbalance of characteristics of battery characteristics. Some batteries are deeply discharged, but others are not fully used, and therefore use ratios of electric energy are reduced, and traveling distance is affected. Furthermore, if any battery breaks down, the whole series circuit can be affected. System efficiency can be improved on the basis of the same voltage class; next, a large scale of battery set does not need connecting in series, and use ratios of electrical energy and reliability of the electrical energy are improved so as to bring convenience to power source management; and in addition, output voltages are more close to a sinusoidal wave, harmonic characteristics of the output voltages and currents are good, total harmonic distortion (THD) is small, insulative impact on a motor is small, and service life of the motor can be improved.

Description

Cascade mesohigh electric automobile current transformer topology and control method thereof

The design capacity of the automobile controller of hybrid power or pure electric bus, heavy load truck progressively is promoted to hundreds of kVA from tens kVA.The electric pressure of series battery has been promoted to maximum 600V to 1000V, has namely reached the DC bus-bar voltage grade of technical grade two level controllers, alternating current asynchronous or the permagnetic synchronous motor of adaptive 380V line electric pressure.Traditional current transformer of this grade generally adopts the IGBT module of 1200V or 1700V electric pressure as switching device, and the dc bus end adopts the battery pack series connection.If adopt 1.2V monomer Ni-MH battery, then need the series connection of 500-800 joint; As adopt the 3V single lithium battery, then need the series connection of 200-300 joint.

A large amount of series connection of battery pack have brought a lot of problems, make the voltage difference of each battery in the series loop such as the unbalanced meeting of battery behavior, some battery deep discharge in the use, and other also have a large amount of electric energy to fail to take full advantage of, and then reduced the utilance of electric energy, influence distance travelled.In addition, if any battery breaks down, whole series loop all can be affected.

And if with the reduction of battery voltage grade, in order to satisfy power demand, then need to improve the operating current of system, and adopt low-voltage, large-current electric machine.Doing has so on the one hand increased line loss, and this type of motor is expensive.

The present invention adopts H bridge cascading topological structure, and one side is elevator system direct voltage grade as much as possible, has reduced current class, thereby has reduced line loss, improves system effectiveness; Do not need the series connection of large-scale battery pack on the other hand, promote utilization rate of electrical and the reliability of battery pack, and bring convenience for the power management of battery pack.The A-battery group is adopted in the input of many level cascading topological structure, as the 48-72V battery pack.Switching device is selected low pressure MOSFET.Each cascade unit is independently-powered by battery pack, and is separate between at different levels, therefore do not have large-scale battery pack series connection.By phase-shift PWM modulation, the importation between the receipts or other documents in duplicate at different levels unit isolates mutually, and the output voltage series connection realizes high pressure output, drive motors.

The cascade output voltage is many level, and than traditional more approaching sine of two level converter output voltages, output voltage and current harmonics characteristic are good, and THD is little.In addition, because the output of many level, voltage change ratio is far smaller than traditional two level circuits, and is therefore little to the impact of electrical machine insulation, the insulated part useful life that can improve motor.

Be example with 72V battery pack and corresponding A cascade unit thereof: 5 grades of cascades can realize the 360V direct voltage, are fit to drive all kinds of alternating current machines of 220V line electric pressure.8 grades of cascades can realize the 576V direct voltage, are fit to drive all kinds of alternating current machines of 380V line electric pressure.14 grades of cascades can realize the 1000V direct voltage, are fit to all kinds of alternating current machines of line voltage 690V.

Each cascade unit adopts low pressure MOSFET to replace traditional IGBT module, though quantity is many, overall cost still is lower than the high pressure IGBT module.In addition, because the cost of equal other 380V/690V motor of power stage is far smaller than the low-voltage, high-current motor, the cost of whole system has obtained declining to a great extent.

Phase-shifting carrier wave PWM modulation is generally adopted in the modulation of Cascade H bridge topological structure.Phase-shifting carrier wave PWM modulator approach is a kind of distortion of conventional P WM modulation, with carrier phase 360 ^o/ N, wherein N is the quantity of Cascade H bridge module.Carrier wave after the phase shift is compared respectively at modulating wave, thereby draw the output duty cycle waveform.The output waveform stack of each module can obtain high pressure output, drives all kinds of alternating current machines.The output line voltage waveform as shown in Figure 6.

Among Fig. 6, each output bridge arm voltage is the stack of each module output voltage, and computing formula as shown in Figure 7.

Suppose that each A-battery group voltage is E, the output phase voltage of a n level H bridge cascaded topology can be+nE so ,+(n-1) E ,+(n-2) E, 0 ,-(n-2) E ,-(n-1) E and-nE.Total output level number is 2n+1, and n is the cascade module number.

Fig. 1 is H bridge cascading topological structure figure

Fig. 2 is based on the system framework figure of H bridge cascaded topology

Fig. 3 is H bridge cellular construction figure

Fig. 4 is H bridge unit output state figure

Fig. 5 is phase-shifting carrier wave PWM modulation schematic diagram

Fig. 6 is H bridge cascaded topology output line voltage schematic diagram

Fig. 7 is H bridge cascaded topology output phase voltage calculation formula

Claims

1. electric vehicle controller topological structure that adopts the cascade of H bridge, as shown in Figure 1.

2. can be known by inference by claim 1, adopt the electric vehicle controller system framework of H bridge cascade structure as shown in Figure 2.

3. can be known by inference by claim 1,2, adopt the basic modulating unit structure of electric automobile current transformer of H bridge cascade structure and the on off state of basic modulating unit to concern as shown in Figure 3, Figure 4.

4. can be known by inference by claim 1,3, adopt the electric automobile current transformer modulator approach of H bridge cascade structure can adopt phase-shifting carrier wave PWM, as shown in Figure 5.