The method of wheel anti-lock slide and urban transport drivers of passenger vehicles operated by chopper and DC motor
A romanian company was development a method of wheel anti-lock and slide of the start and does not require the use of speed transducers. It can be implemented on any electric powered vehicle with chopper and DC engine, with minimal costs, providing a robust solution without the need for maintenance.
The company was developing a concept that is based on the use of the modern IGBT transistors, keeping the continuous current engines. It was obtained, in this way, easier electric drives, very compact and which offer a very precise continuous electronic control, without stages, implicitly without current leaps that will produce mechanic shocks. The elimination of the electric resistances from the power electronics circuit and their replacement with the choppers actually represent the elimination of the losses through the heat dissipation, especially at reduced speed, which is characteristic to the urban traffic.
Moreover, the chopper driving allows to the continuous current engine to pass in a generator mode, especially when it brakes. So, the kinetic energy of the tramway is transformed in electric energy that is recovered in the power line. This energy is consumed by other vehicles that are powered from the same line. In the case in which there are no other consumers, the braking energy will be dissipated on a resistance.
The continuous electronic control of the current respectively of the engine torque and very fast electronic protections realized with the chopper lead on one hand to the increase of the reliability and on the other hand to the increase of the safety in the exploitation of the modern vehicle.
The modernization of the electrical traction vehicles supposes the replacement of the motor-generator group for the power supply of the auxiliary services with a static converter and the management, command and the control of the entire vehicle by the on board computer.
The on board computer offers a diagnosis system that, with the help of a PC, offers the possibility of the visualization of the measurements and relevant data and faults as well as their localization.
In a normal function regime the chopper is controlled by the on board computer through the CAN open bus. For an easier troubleshooting, the command module of the chopper has an isolated communication port, through which the data packages are being sent to a terminal (usually a personal computer). The data sent can be seen on-line, they can be stored for an ulterior analysis.
The main functions of the chopper are:
1. provides power supply for the driving motors corresponding to the running-braking regime;
2. unitary construction, mono-block;
3. CAN open communication with the on board computer for receiving the commands and the permanent monitoring of the tramway's status;
4. the chopper can function in a fault regime if the board computer is damaged or communication is lost; this regime is useful to drive the vehicle to the depot for troubleshooting;
5. the command module of the chopper can store information that can easily be used for the maintenance of the vehicle (function hours, mileages, maximum speed, minor faults or critical faults, etc.).
Traction control chopper with IGBT
Input voltage: +20%;-30%, Input 150KW, Construction modular, Location under floor or on the roof, Cooling forced ventilation; Characteristics - IGBT-technology without contactors to change the start - brake mode combined generative and the static brake control signal: optical fibber protections: over tension, short-circuit, over temperature, Control unit with DSP: Construction PBB boards, plug-in unit, Cooling: natural convection, Supply: 24VDC (+/- 20%).
Auxiliary power supply static converter:
Nominal output power: 5KVA, Input voltage: VDC (+20%;-30%), Output voltage: 24-30VDC adjustable, Maximum output: 180ADC, Options: Output: Tree phase voltage 400VAC, 50Hz Nominal power: on request
Advantages of the chopper:
• saving energy up to 40%,
• the increase of the reliability
• the maintenance reduction
• the increase of safety in exploitation and in passengers comfort
• the fulfillment of the requirements of a modern electrical drives used in the urban public transport
Another advantage offered by the use of the chopper is the elimination of an important number of electromagnetic contactors from the classical circuit. In the electrical scheme there were kept only the contactors that change the sense which are (anyway) rarely controlled (when going backwards). The commutation between running regime and brake regime, which is frequently used, is made with IGBT transistor.
In this way, due to the net superior reliability of the IGBT transistors compared to the electromagnetic contactors, the chopper modernization increases the reliability of the vehicle and reduces the costs and the maintenance time.
Available for demonstration - field tested