LS Workshop

Grid-side Inverter Control Scheme

1. Electric Circuit Model

2. Mathematical Model

3. Controlled Object

4. Control System Scheme

Motor-side Inverter Control Scheme

1. DQ Mathematical Model

2. Electric Circuit Model

3. Control System Scheme Model

4. Speed Sensorless Observer

Cascade topology-based medium voltage motor drive (MVD) Technology

Key Players of MVD Industry

The DCDC Converter Circuit Design in Electrical Vehicle

1. DCDC Converter Design- spec

Input voltage： 210Vdc~410Vdc

Output voltage： 14V1500W

Output voltage adjustable range: 12~16Vdc, PWM signal control

Regulation： ±1%

Start up overshoot： ± 5%

Transient response： 1ms， 0%~50%~0% 1000A/s

0%~100%~0% 1000A/S

Ripple： 200mV

Efficiency： 92%

Protection function： Input under voltage: Automatic recover

Input over voltage: Automatic recover

Output under voltage: Automatic recover

Output over voltage: Latch

Over load/short circuit: Automatic recover

Over temperature: Automatic recover

Remote control: TTL level voltage

Fault alarm: OC alarm

Mechanical outline： 280mm×200mm×70mm

Weight： 3.6kg

Operation temperature： -40~85 ℃

Cooling： Water cooling ( water temperature: 75℃)

( water press is from 0.02Mpa)

EMC： CISPR 25, Level 4

Vibration： QC/T 413-2002 3.12, Not on the Engine in engine

cabinet

Protection： IP66

2. DCDC Converter Design- Circuit

(1). EMI stage:

Four common mode inductor: 2.1mH, R7K, T25X15X10, 1.2mm, 23T

(2). Buck+ open loop interleaved LLC

Buck: Mosfet: 20N60, Diode:R1560

Inductor: 2X56uH, CS234090, FeSiAl, 1.0mmX3, 20T

UC2843 IRS21834
Switching frequency: 100KHz

(3). Open loop Interleaved LLC

Primary Mosfet: IRF38N20, Synchronous Rectifier: IRF3805

Lm: 18uH, Lr: 2.6uH, Cr:39nF

Lr: 2.6uH, PQ26, PC95, 0.25X3.5X4, 3T

Transformer: ER30, PC95, Primary 4OZ PCBX2, 5T

Secondary 0.2X4.5mm copperX6, 1T

Output Capacitor: 10uFx17

Switch frequency: 300kHz

(4). Auxiliary Power Supply

Transformer: EFD20, PC40

Mosfet: 9R1K20

Control IC: UC2844

Switching frequency: 130KHz

For the calculation of the Inductance of the chokes to be used to parallel the two inverters, we take into consideration the following two possibilities:-

1. The corresponding parallel arms +ve & -ve are connected directly to one another (i.e. using busbars) as a result of which the inductance at the input is negligible.

2. The corresponding paralllel arms +ve & -ve are both connected to the output of the bridge rectifier as a result of which the inductance of these connections must be taken into consideration.

In the diagrams, for clarity, only one arm of each inverter has been shown and the possible connection of the DC busbars at the inut of each arm. It must be understood that for the entire system, there would be 3 such arms per inverter, giving therefore the 3-phase output.

Case 1

Direction connection of DC Inputs of paralleled Inverters

Here we have,

maximum value of Vdc = 850V

maximum delay between switching OFF of one TOP IGBT and switching ON of one BOT IGBT, Dt = 125 ns (i.e. the maximum possible time delay between the control pulse being received at the IGBTs and the IGBTs switching as a result)

say, maximum allowed DiSC = 10 A

Therefore,

Lac = 850 /(2 x 10)x 0.125 µH

= 42.5 * 0.125 µH

= 5.3125 µH

Lac = approx 5 µH

Case 2

Connection of Inputs of paralleled Inverters to Input bridge rectifier.

In this case, the additional inductance at the outputs of the bridge recifier will serve another purpose i.e. to smoothen the ripples in the output of the bridge circuit.