Showing papers on "Dynamic braking published in 1988"

Alternating current motor control system with emergency control responsive to failure of power supply

Abstract: A control system for an alternating current motor, such as an elevator hoisting induction motor, in response to failure of power supply, such as service interruption, phase open and so forth, performs in a first emergency control mode and in a second emergency control mode. In the first emergency control mode operation, dynamic braking is used to decelerate the motor. On the other hand, in the second emergency mode, triggered while the motor is driven in regeneration mode to recirculate regenerated power to decelerate the motor, a mechanical brake is applied. During second emergency control mode operation, power supply condition is monitored to detect failure of the power supply for switching control mode from the second emergency control mode to the first emergency control mode. Switching from the second emergency control mode to the first emergency control mode assures synchroneous operation of an inverter and the motor after resumption of power supply to the motor in cases where the power failure is short in duration.

Hydraulic braking system

Abstract: A hydraulic braking system capable of reducing the brake pedal stroke is provided by adding to the basic hydraulic braking system. The adding system is able to selectively execute the reduction of brake pedal stroke and, at the same time, capable of selectively adding anti-lock function and anti-slip function by including the changeover valves or opening and closing valves to the system. An auxiliary hydraulic pressure generator having a power hydraulic pressure source and regulator is interposed in the hydraulic conduit of at least one circuit, and an outlet port of the regulator is communicated to the wheel cylinders for connecting to the hydraulic conduit of the circuit. Brake pedal stroke can be reduced by inclusion of other conduit arrangements for adding the auxiliary hydraulic pressure generator and, at the same time, the changeover valve, anti-lock control changeover valve, and normally closed valve are selectively releasably added or mounted to the system, so that a brake system having short brake pedal stroke and sporty feeling can be obtained by low cost system ensuring desired braking operation. Additionally, anti-slip control for preventing the slipping of driving wheels can be added.

Electric motor brake

Abstract: The subject invention is an electric motor brake which uses a simplified circuit enabling a timed injection of DC voltage into the motor windings of an induction motor. This DC voltage acts as a dynamic braking force and will bring the rotor, and whatever is connected to it, to a stop in a rapid fashion. An additional advantage of the invention is that it may be constructed and used as a stand alone device which may be attached to any electrical induction motor to achieve the desired braking effect. A further feature of the invention is the provision of a timing circuit that it is designed to be user adjusted to achieve the maximum possible effect rather than using a fixed design which would result in a compromise in order to be suited for wide usage.

Braking control system for thermal printhead

Abstract: A thermal printer in which a thermal head block is moved into and out of pressure contact with a platen roller through a cam mechanism which is driven by a controlled DC motor. The DC motor alternately effects dynamic braking and negative-phase braking before the thermal head is pressed upon the platen roller.

Device for braking a bicycle

Abstract: A device for retarding a bicycle having a braking system, the device incls an additional braking device independent of the braking system of the bicycle. A brake is associated with the additional braking device and a traction lever is provided for controlling the additional braking device which is adapted to be locked in a cable traction position. Transmission control cable is connected between the traction lever and the brake for controlling the additional braking device, and a force limiting device is positioned between the lever the additional brake for adjusting the additional braking device.

Braking system for two-wheelers

Abstract: A braking system for two-wheelers is provided with a normal-duty actuation member which acts on both a front braking assembly and a rear braking assembly, and with an emergency actuation member which acts on one only of said braking assemblies; means are provided for balancing the actuation force applied by the normal-duty actuation member and the actuation force applied by the emergency actuation member on the common braking assembly, which enable the greater of the two braking actions to be applied as the braking action, for the purpose of preventing the jamming, and hence the skidding of the vehicle wheel on which such common braking assembly acts.

A microcomputer-based speed controller for lift drives

Abstract: A microcomputer-based speed controller for squirrel-cage induction motors for lift drives is presented, designed as a replacement for the classical analog versions. The appropriate speed control is achieved by phase-cut stator voltage control and by dynamic braking with DC current injection. Both actions are implemented by standard analog phase-control integrated circuits and 8-bit D/A (digital-to-analog) converters. A speed feedback signal is generated by a noisy tachogenerator, so that a low-pass antialiasing filter, followed by a true-averager circuit, is involved for proper signal conditioning. The true averager provides high rejection of the mains frequency and its higher harmonics. The built-in self-test routines and associated circuitry provide part-by-part testing of the hardware. This together with simple diagnosis, supports faster installation and more efficient troubleshooting. Complete firmware is organized in the shape of interrupt-driven routines, which are reentered at every mains zero crossing in the positive direction. A reference-speed profile with the shape of parabola is used to achieve a constant acceleration-time gradient. A discrete proportional integral (PI) control algorithm with lag-lead frequency compensation gives acceptable control accuracy, stability and robustness. >

Method for controlling the braking intensity on rail vehicles

Abstract: A method for controlling the braking intensity on rail vehicles in which technical means of conventional pneumatic brake systems are present and are supplemented by electronic means and electropneumatic actuators in order to ensure simultaneously interaction between conventional and electronically controlled brakes. In this process, a signal which is transmitted to the vehicle and corresponds to the selected level of braking intensity is converted by means of a transmission element into a control variable for the continuous control of the braking intensity.

The Braking Performance of Commercial Vehicles while Cornering with and without an Anti-Lock System

Abstract: One of the most common and technically interesting handling maneuvers in everyday service is braking in a turn. For this reason the braking performance in a turn is one of the most important points in the vehicle concept, which has to be precisely observed when designing a motor vehicle. The reactions of the vehicle must demonstrate, after the corresponding optimizations on the vehicle have been completed, a most favorable compromise between steerability, directional stability and deceleration (A).

Device for reducing the braking torque of internal-combustion engines in vehicles

Abstract: 1. A device for reducing the braking torque of internal combustion engines in motor vehicles in the change from pulling to overrun operation, the device having a power-regulating element the return of which in the direction of its rest position is influenceable by a damper (7) which is effective when a drive connection exists between the internal combustion engine (1) and the driven wheels of the motor vehicle, characterized in that the damper (7) is so formed that, throughout the displacement of the power-regulating element (2) in the direction of its rest position, it is continously effective in the direction of a reduction of the speed of the displacement movement of the power-regulating element compared with the case of operation without the damper being effective, and that the damper is ineffective when there is no drive connection between the internal combustion engine and the driven wheels of the motor vehicle.

Braking of three-phase induction motor

Abstract: PURPOSE:To allow even a motor of expanded capacity to perform braking, by separating a stator winding from power source and at the same time performing dynamic braking, and then by interrupting DC conduction by a centrifugal switch to actuate an electromagnetic brake. CONSTITUTION:When a motor 3 is stopped, it is interrupted from a power source 1 by opening a contact 5A. At the same time by closing contacts 5b and 5c, the motor 3 is charged to a DC power source 4. By exciting two-phase of a winding 3a, poles are formed to perform dynamic braking. After braking when the motor comes up with a definite revolution, a centrifugal switch 9 actuates to interrupt the conduction to the stator winding 3a, while the power source of an electromagnetic brake 6 is charged.

Kraftuebertragungsvorrichtung fuer fahrzeug mit vierradantrieb

Abstract: A power transmitting apparatus for a four-wheel-drive vehicle utilizes dynamic braking of an electric motor. The power transmitting apparatus includes a main transmitting mechanism 43 for directly transmitting torque of a power unit 41 to main drive wheels 44, an auxiliary transmitting mechanism having a power transmitting shaft 42 for transmitting torque of the power unit to auxiliary drive wheels 47, an electric motor 1 disposed in the auxiliary transmitting mechanism and having a rotor 2 and a stator 3, one of the rotor and the stator having output terminals, and a resistor 6 connected to the output terminals. The motor operates as a generator. The kinetic energy produced by the difference between the rotational speeds of the stator and the rotor is converted to electric energy, which is dissipated as heat by the resistor. Torque commensurate with the differential speed is produced from the output shaft 4 of the motor.

Preliminary study of brake pedal location accuracy

Abstract: Three experiments of brake pedal location accuracy were conducted using 24 subject drivers The first experiment tested the accuracy of recall of drivers for the brake pedal location of the vehicle with which they were very familiar The second experiment examined the accuracy of recall for a brake pedal location with which they had recent practice The last experiment attempted to determine if practice with one brake pedal location would interfere with the accuracy of reproduction of a newly learned pedal location The results of the experiments indicate that subject drivers have difficulty in reproducing the location of brake pedals This difficulty exists for familiar brake pedal locations as well as newly learned brake pedal locations Further there is an indication that practice with one brake pedal location may influence the accuracy of reproducing the location one newly learned

Some problems of vehicle's brakes and braking

Abstract: SUMMARY The paper presents the results of simulation of braking process of vehicle. The vehicle-driver-road system was investigated in order to choose the concept of anti-locking device. Final choice of the control of such a device was obtained by means of computer simulation. Its idea was based on the analysis of wheel's angular velocity compared with programmed velocity of each of them. Laboratory and road tests confirmed the correctness of anti-locking control and showed the protection of wheels against locking during panic braking.

Electric rolling stock controller

Abstract: PURPOSE:To prevent the overvoltage condition of a chopper due to the repetition of sudden increase and decrease of a regenerative load, by a method wherein a dynamic brake chopper is controlled by a conduction rate in accordance with an actual regenerative current signal based on the voltage of a filter capacitor and a conduction rate of a given value or more. CONSTITUTION:Upon dynamic braking, a conduction rate control commanding value is operated by an operating circuit 10a in a conduction rat control unit 10 based on a difference between a line voltage pattern signal ECO and a filter capacitor voltage EC. then, a control signal (r) is outputted from a conduction rate control circuit 10b to a dynamic brake chopper 1 so as to obtain the commanded value. At the same time, a difference between an actual regenerative brake current I and a brake pattern signal Ipb as well as a fixed conduction rate and a bias commanding signal are inputted into the operating circuit 10a at all times. In this way, the chopper will never be brought into overvoltage with respect to the fluctuation of the filter capacitor voltage due to the repetition of sudden increase and decrease of the regenerative load.

Braking controller for electric automobile

Abstract: PURPOSE:To miniaturize and lighten a mechanical braking means by ON-OFF controlling a switching element so that said element supplies an induction motor with a dynamic braking DC power when it receives a fault signal of said switching element. CONSTITUTION:If the title apparatus is in good order, switches 18a, 20a, 22a are connected to an output terminal side of a function generator 16 for normal travel and respective semiconductor devices 28a, 28b, 30a, 30b, 32a, 32b of a power converter 26 are ON-OFF controlled so that a motor drive corresponding to a torque command T is performed. If a fault detector 44 detects any trouble, a defective semiconductor device is decided and a DC braking mode is selected. On the basis of said decision and selection, the fault detector 44 changes the switches 18a, 20a, 22a to an output terminal side of the function generator 46. Consequently, a switching signal for DC braking of a motor 42 is obtained as the output of comparators 18, 20, 22.

DC Dynamic Braking Performance of Linear Induction Motors

Abstract: Polyphase double-sided flat linear induction motor with non-magnetic conducting wide secondary operating in the dc dynamic braking mode is analyzed using field theory techniques. One-dimensional, One-dimensional space harmonic, Two-dimensional in the secondary plane, and Three-dimensional models are employed and performance is predicted. Predicted braking thrusts are compared to experimental results obtained elsewhere.

Method for braking rolled bars and an approach roller table for cooling beds for carrying out the method

Abstract: A description is given of a method for braking moving rolled bars of differing lengths in the region of the approach roller table of cooling beds, in which method the braking force is provided by friction between the respective surface of the rolled bar and static and/or dynamic braking surfaces, e.g. those of braking slides and braking drivers, acting on it. Minimum length dimensions are achieved for a cooling-bed installation because the braking force on the rolled bars up to a predetermined limiting length is provided exclusively by static braking surfaces. Rolled bars with a length that exceeds this limiting length, on the other hand, are additionally subjected to the action of dynamic braking surfaces. The duration and/or intensity of action of the dynamic braking surfaces is/are determined by the difference between a likewise predetermined maximum length of rolled bar and the particular effective length of rolled bar.

High voltage, outdoor, air cooled, dynamic braking resistors and power distribution system incorporating the same

Abstract: An electrical resistor having first and second cylindrical resistance windings helically wound closely adjacent one another about a common axis and wound in opposite directions about such axis. The helical windings of the resistor are connected in parallel and the resistor is provided with terminals for placing it in series with a circuit to provide a resistance in such circuit. The resistors are used in a power distribution system that includes a first system connected to a second system by a tie line. The resistors referred to as braking resistors are located adjacent at least one of the power sources and are connected to the tie line through one or more circuit breakers.

Computation of D.C. Motor Dynamic Braking Performance

Abstract: A procedure is described for the computation of speed-time curves during dynamic braking of a separately-excited d.c. motor which includes the non-linear effects of magnetic saturation and machine losses. The application of the procedure to student assignment work is briefly discussed.

Dynamic braking control system for tape driving system

Abstract: In a tape drive system, a dynamic brake control circuit provides dynamic braking for slowing and stopping an associated tape reel and motor system in the event of a power failure Upon sensing a power failure, the electrical energy stored in a capacitor supplies electrical energy to enable the control circuit, which in turn supplies a controlled conductive path for the flow of a dynamic braking current due to the back electromotive force signal generated by the motor, to effect the controlled dynamic braking of the drive motor to a stop

Speed controller for electric motorcar

Abstract: PURPOSE:To improve operability, by a method wherein braking mode is set at first and, then, a motor is reversed by the stop detecting signal of the motor when the operation of an electric motorcar is switched from forward movement into rearward movement. CONSTITUTION:When a stick is operated to the direction of forward movement, an operation signal is amplified by a control amplifier 4 and, thereafter, the amplified signal is inputted into the gate of a transistor 3. A current, proportional to the voltage of the gate, is conducted through a motor 1. Next, when the stick is operated from the direction of forward movement into the direction of rearward movement, an operation signal is amplified by the control amplifier 4 and, thereafter, the amplified signal is supplied to the gate of the transistor 2. Accordingly, dynamic braking is generated in the rotation of the normal direction of the motor 1. When the rotation of the motor 1 is stopped, the voltage of a point A is increased and the output of an operation amplifier 10 becomes 'H'. According to this method, the contact of a relay 13 is switched and the current of the direction of reversing the motor 1 may be conducted.

Power system for supplying power to a motor.

Abstract: A pulsating D.C. voltage is developed by a rectifier (86) and is filtered by a capacitor (100) to facilitate application of a relatively smooth, enhanced D.C. voltage to a motor (106). The charged voltage of capacitor (100) is applied across a series circuit which includes a rheostat (118), a resistor (126) and motor (106). When the CEMF of motor (106) drops as a result of a decrease in motor speed, a diac (122) is biased through the voltage appearing across rheostat (118) and resistor (126) to cause an SCR (116) to fire. When SCR (116) fires, the voltage of capacitor (100) supplies a boost of power to motor (106) to overcome the decrease in motor speed. A circuit (212) prevents an overspeed of motor (106) from occurring while braking circuits (264, 266 and 268) provide for a dynamic braking effect when the motor is a universal motor.