Abstract:
Transportation apparatus, such as escalators and moving walks, having controlled stopping characteristics. Deceleration is directly regulated via a deceleration servo loop which provides a current reference signal for an inner current loop. Brake current limiting prior to the controlled stop, as well as mechanically limiting the maximum brake gap, results in faster transient response, and a more linear braking torque versus brake current characteristics. Multiple drive units operate from a common deceleration reference signal, while having independent servo loops each operating from a "local" deceleration signal.
Abstract:
An elevator system including an elevator car mounted for guided movement in a vertical travel path. A signal related to car velocity is modified by a signal related to car acceleration. The modified velocity signal is utilized in a speed monitoring system which monitors car speed as a function of car position adjacent the travel limits of the elevator car.
Abstract:
An elevator system including an elevator car and counterweight mounted for movement in a structure by a traction drive arrangement which includes a drive sheave and a drive motor. A first tachometer provides signals responsive to the drive motor and a second tachometer provides signals responsive to movement of the elevator car. The signals from the first and second tachometers are used in both functional and monitoring circuits to control the operation of the elevator system in a highly efficient self-checking manner.
Abstract:
A PWM inverter in which the maximum three-phase RMS pole-to-pole output voltage is increased, to more efficiently utilize a fixed DC power supply, by generating substantially sinusoidal changing pole voltages having no values within predetermined zones adjacent to each power supply limit, and by switching each pole voltage to a power supply limit for a predetermined number of electrical degrees during each half cycle, resulting in step changes in the pole voltage waveforms from the substantially sinusoidal changing waveform to a fixed power supply limit.
Abstract:
An elevator system including an elevator car, and control apparatus for controlling its speed, including a floor selector and a speed pattern generator. The speed pattern generator provides a running speed pattern, and a slowdown speed pattern. A smooth transfer from the running speed pattern to the slowdown speed pattern is achieved by the generation of first and second deceleration signals, and a transfer signal. When the floor selector issues a slowdown signal, the slowdown speed pattern is initiated and the first deceleration signal causes the running speed pattern to have a zero rate of change. First and second different relationships between the running speed pattern and the slowdown speed pattern then successively cause the issuance of the second deceleration signal and the transfer signal, with the second deceleration signal causing the running speed pattern to have a predetermined constant rate of change, less than that of the slowdown speed pattern, such that the patterns intersect. Pattern equality causes the issuance of the transfer signal, which initiates the substitution of the slowdown speed pattern for the running speed pattern.
Abstract:
An elevator system including a comparator which develops a control signal responsive to the actual versus the designed performance of the elevator car as it approaches a floor at which it is to stop. This control signal is used in a monitoring and protective arrangement which controls pre-opening of the doors before the elevator car stops at a floor, as well as providing additional protection relative to the operation of the elevator car after it has made an inaccurate landing, and back-up protection for any movement of the elevator car with its doors open.
Abstract:
An elevator system including an elevator car, a drive motor for the elevator car, a power supply for the drive motor which includes a three-phase source of alternating potential, and a monitor for the three-phase source. The monitor discriminates between a malfunction of the three-phase source which should initiate shutdown of the elevator system, and a momentary disturbance which should be ignored.
Abstract:
A method and apparatus for smoothly stopping an elevator car at a target floor in an elevator system which utilizes a speed pattern to control car speed via a speed feedback control loop. When the elevator car reaches a predetermined slowdown point relative to a target floor, the speed pattern is changed towards a predetermined minimum non-zero value, with the non-zero value being selected to insure that the car will reach the floor in the event of error in the arrangement used to change the value of the speed pattern. The speed pattern value is then independently forced to a value indicative of zero car speed in response to a detector which detects the actual presence of the elevator car as it reaches a predetermined small dimension from the target floor, to stop the car at floor level, before a holding brake is applied.
Abstract:
A method for providing a load compensation signal for the drive motor control loop of a traction elevator system which includes an elevator car, a counterweight, and a drive which includes a drive motor, brake, and traction drive sheave. The brake is mounted to provide an indication of the direction of unbalanced brake torque, with the method including the step of detecting unbalanced brake torque when the elevator car is stationary. A car load compensation signal is provided in response to the detecting step, with the compensation signal transferring the unbalanced torque from the brake to the drive motor, building up the motor current to provide motor torque sufficient to hold the car stationary while the brake torque is reduced to zero. The method then continues by using the motor current to provide car loading signals for use by the supervisory control portion of the elevator system.
Abstract:
A method and apparatus for providing a load compensation signal for the drive motor control loop of a traction elevator system which includes an elevator car having a load responsive platform and a counterweight. The load compensation signal transfers unbalanced torque from the system brake to the drive motor at the start of the run, to provide smooth starts. The load compensation signal is heavily filtered to provide a response time which will follow changes in car loading but too slow to affect car dynamics. Thus, the load compensation signal is continuously connected to the motor control loop, eliminating switches and memories, and enabling the compensation signal to directly aid car landing. Non-linearities in the load responsive platform are partially compensated for by three initial adjustments, and a fourth adjustment is provided for periodically offsetting changes due to ageing of platform isolation materials.The load compensation signal may be added directly to the motor control loop, or further processed to account for hoist cable weight compensation error at the location of the elevator car.