Variable-voltage variable-frequency elevator control apparatus
First Claim
1. An improved variable-voltage variable-frequency elevator control apparatus of the type having a 3-phase AC main power source, a power running converter with its AC input side connected to said main power source, an inverter of the pulse width modulation type with its DC input side connected to the DC output side of said power running converter, an induction motor connected to the AC output side of said inverter, an emergency generating unit connected to the AC input side of said power running converter, a regenerated power DC to AC converter with its input side connected to the DC input side of said inverter and with its output side connected to the AC input side power running converter, wherein the improvement comprises:
- means for consuming regenerated power connected across the DC input side of said inverter; and
control means for turning said means for consuming regenerated power on during emergency regenerative braking and off at other times and for turning said regenerated power converter on during normal regenerative braking and off and blocking the transmission of DC power from the DC input side of the regenerated power converter to its AC output side at other times, said control means turning said means for consuming regenerated power on and turning said regenerated power converter off instantaneously at the same time responsive to detecting abnormalities in the power from said power source and shifting to the emergency generating unit, and a regenerative braking condition.
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Accused Products
Abstract
A variable-voltage variable-frequency elevator control apparatus is disclosed in which a circuit for the consumption of regenerated power produced during regenerative braking is provided on the DC side of the apparatus rather than on the AC side. During regenerative braking with an emergency generating unit in operation, regenerated power is consumed by the consumption circuit on the DC side of the circuit and is prevented from being returned to the emergency generating unit. This prevents the production of voltage notches commonly produced during regenerative braking by thyristor commutation in conventional circuits. Because no voltage notches are produced, a reduction in the size of the emergency generating unit can be achieved. In addition, since it consumes DC power rather than 3-phase AC power, the consumption circuit requires fewer elements than in conventional control apparatuses.
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Citations
10 Claims
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1. An improved variable-voltage variable-frequency elevator control apparatus of the type having a 3-phase AC main power source, a power running converter with its AC input side connected to said main power source, an inverter of the pulse width modulation type with its DC input side connected to the DC output side of said power running converter, an induction motor connected to the AC output side of said inverter, an emergency generating unit connected to the AC input side of said power running converter, a regenerated power DC to AC converter with its input side connected to the DC input side of said inverter and with its output side connected to the AC input side power running converter, wherein the improvement comprises:
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means for consuming regenerated power connected across the DC input side of said inverter; and control means for turning said means for consuming regenerated power on during emergency regenerative braking and off at other times and for turning said regenerated power converter on during normal regenerative braking and off and blocking the transmission of DC power from the DC input side of the regenerated power converter to its AC output side at other times, said control means turning said means for consuming regenerated power on and turning said regenerated power converter off instantaneously at the same time responsive to detecting abnormalities in the power from said power source and shifting to the emergency generating unit, and a regenerative braking condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification