US 5,323,095 A · Propulsion and electric braking system for electric traction motor vehicle

Abstract

A system and method for controlling power transfer between an internal combustion driven electrical power generator and a direct current (DC) motor. In one form, the invention includes control of a power inverter in a manner to restrict current through a winding of the generator to a predetermined polarity. The inverter includes a plurality of gate controlled switching devices which are selectively energized to allow current to free wheel through the motor during at least some portion of each alternating voltage cycle of the generator. In another form, a plurality of resistors are connected in series with an inverter and a DC motor with each resistor including a switching device for bypassing current around the associated resistor. In this form, resistors can be selectively inserted into the series path during electrical braking so that a maximum amount of electrical energy can be transferred to the generator through the inverter without exceeding the voltage limits of the inverter during high speed braking. Regenerative braking is further maximized during low speed or reduced braking requirements by removing resistors from the series current path.

Claims11

Dependent claims

A system for regenerative and dynamic electrical braking of an electrically powered traction vehicle, the vehicle including an alternating current (AC) power source connected to be driven by an internal combustion engine, a full wave controlled rectifier bridge circuit connected to electrical power output terminals of the power source for converting the output AC power to unidirectional current (DC) power, and at least one DC motor having an armature connected in electrical circuit with the rectifier bridge circuit, the system comprising:

dynamic braking resistance means operatively connected in series electrical circuit between the DC motor armature and the rectifier bridge circuit;
and
switching means, operatively connected in parallel circuit arrangement with the resistance means, for selectively controlling introduction of the resistance means into the series electrical circuit, the electrical energy developed by the DC motor armature during electrical braking of the vehicle being selectively divided between regenerative and dynamic braking by control of the switching means.

A method for operating a full wave controlled rectifier alternating current (AC) to direct current (DC) power bridge circuit for minimizing ripple currents in a DC load, the bridge circuit including at least four controlled rectifiers for selectively coupling an AC source to the DC load in a manner to regulate load current through the DC load to a preselected value, the method comprising the steps of:

(a) gating a series combination of at least two controlled rectifiers into conduction for circulating load current through the DC load in a current path bypassing the AC source;
(b) selectively gating another of the controlled rectifiers into conduction for establishing a current path through the AC source for the load current;
(c) gating still another of the controlled rectifiers into conduction in series with the another of the controlled rectifiers for bypassing load current about the AC source when the AC source changes voltage polarity;
and
(d) alternately repeating the steps of selectively gating and gating still another of the controlled rectifiers at preselected times for regulating the DC load current to the preselected value.

2 more elements

Dependencies are inferred from the claim text.

Propulsion and electric braking system for electric traction motor vehicle

Life of this patent

Propulsion and electric braking system for electric traction motor vehicle

Life of this patent

Abstract

Claims11