DESIGN AND IMPLEMENTATION OF A BI-DIRECTIONAL POWER CONVETER

FOR ELECTRIC BIKE WITH CHARGING FEATURES

INTRODUCTION Recently, in order to comply with the policies of energy

saving, carbon reduction, and environmental protection, all of the electric equipments and energies are requested to satisfy the green demand.

However, massive fuel oil vehicles result in serious air pollution and destruction environment.

Therefore, the development of the electric vehicles (EV) or the hybrid electric vehicles (HEV) are becoming important policies in many countries.

The secondary batteries are the main energy sources of the EV. Thus, energy management is the most important key factor in EV or HEV design.

Nowadays, bidirectional converter applied in electric vehicles can provide energy stored in battery for driving motor and offer battery charging or energy recovery.

Many advanced techniques, research results or control strategy related to the bi-directional converter are explored in succession.

EXISTING SYSTEMSThe power management and circuit topologies of single-phase and multi-phase bidirectional converters including non-isolated type and isolated type are all detailed. The non-isolated converters can be categorized into: buck, boost, and buck-boost types, which are low cost, compact size, without transformer, and easy to control due to having common ground. A transformer is still essential based on safety considerations.The buck-boost type bidirectional converters not only possess step down and step up functions, but also can control the energy flow to achieve energy recovery, which is also suitable for many EV design. In order to provide high power and high current output characteristics at instant for electric vehicles, many kinds of secondary batteries are manufactured.Among the existing power batteries, lithium batteries possess higher energy density, lighter weight, and compact size.

PROPOSED SYSTEM

There are many operation mode in proposed system ,including driving of BLDC, charging of battery, and detection of the battery capacity.

There are many common used methods regarding battery charging, such as constant voltage charging, constant current charging, and pulse charging. Besides, many existing techniques of state of charge (SOC) estimation are also proposed, such as open-circuit voltage method, kilometric estimation method, impedance measurement method.

BLOCK DIAGRAM

THE SCHEMATIC OF THE PROPOSED BI-DIRECTIONAL BUCK-BOOST CONVERTER

VOLTAGE REGULATOR CIRCUIT DIAGRAM

BUCK-BOOST CONVERTER EXPLANATION A BUCK-BOOST CONVERTER IS NOTHING BUT

CASCADE CONNECTION OF TWO BASIC CONVERTERS:

1.STEP-DOWN CONVERTER.

2.STEP-UP CONVERTER. THE MAIN APPLICATION .

1. IT REGULATE THE DC POWER SUPPLIES

2. THE NEGATIVE POLARITY OUTPUT MAY BE DESIRED WITH RESPECT TO THE COMMON TERMINAL OF THE IN- PUT VOLTAGE.

3. THE OUT-PUT VOLTAGE CAN BE EITHER HIGHER OR LOWER THAN THE IN PUT VOLTAGE.

BUCK-BOOST CONVERTER

CONTROL STRATEGY OF PIC18F4520 A single-chip PIC18F4520 provided by Microchip was used

to implement a control core for the proposed bi-directional converter.

This PIC has event manager and embedded control features, thereby allowing a sophisticated control algorithm to be implemented for power converting systems.

There are many operating mode in the proposed system, including driving of BLDC, charging of battery, and detection of the battery capacity. Moreover, mathematical operation capability and multi-I/O features are required.

Therefore, the PIC controller is employed to reduce component counts, to simplify controller structure, and

improve the system reliability.

PIC18F4520 PINCONFIGURATION

Sleep modeWatchdog timer (WDT)Code protectionIn-circuit serial programmingIn-circuit debugger

PIC18F Special Features

The Watchdog Timer.:

Suppose you have written a program that is continuously running on a PIC.

Now consider this two situations.: Let us say that the PIC is monitoring an

input. When this input goes high, it jumps to another part of the program. What happen when its not getting high?

The another situation after a long period of time, the program gets stuck somewhere and the PIC gets caught in a loop.

CIRCUIT DIAGRAM

BRUSHLESS DC MOTOR

Similar to a permanent magnet DC motor Rotor is always the permanent magnet (internal or external) Design eliminates the need for brushes by using a more

complex drive circuit Advantages:

High efficiency High reliability Low EMI Good speed control

Disadvantages: May be more expensive than "brushed" DC motors More complex and expensive drive circuit than

"brushed" DC motors

Why a Brushless DC Motor ? Many of the limitations of the classic permanent magnet

"brushed" DC motor are caused by the brushes pressing against the rotating commutator creating friction

As the motor speed is increased, brushes may not remain in contact with the rotating commutator

At higher speeds, brushes have increasing difficulty in maintaining contact

Sparks and electric noise may be created as the brushes encounter flaws in the commutator surface or as the commutator is moving away from the just energized rotor segment

Brushes eventually wear out and require replacement, and the commutator itself is subject to wear and maintenance

Brushless DC motors avoid these problems with a modified design, but require a more complex control system

FLOW CHART

WORK TO BE DONE SO FAR

MOTOR DRIVING INVERTER SHOULD BE SET.

BRUSH LESS DC MOTOR SHOULD BE SET.

RECTIFIER SHOULD BE SET.

WORKDONE SO FARTIMERS PROGRAM HAS BEEN DONE IN

PIC18F4520 AND COMPLIED.

INTRUPT FOR TIMER PROGRAM HAS BEEN COMPLIED.

BATTERY HAS BEEN FIXEDCASCADE BUCK-BOOST

CONVERTER ,HAS BEEN READY .

Hardware Requirements

Inductors, capacitors, transistors, diodes, and Triggering circuits. PIC18F4520

Software Requirements

PSIM/MULTISIM Tools for simulation.TMS320F2812 FLASH programming

softwareWindows Xp: Service pack 2

THANK YOU