Hybrid system of vehicle

Abstract

Disclosed is a hybrid system of vehicle capable of accurately generating an engine output in conformity to a required vehicle driving power and suppressing an electric power loss even when a battery is used for correcting electric power to prevent occurrence of overshoot or undershoot. The hybrid system of vehicle is designed to drive a generator by an engine and supply an electric power generated by the generator directly to a wheel-driving electric motor so as to drive the motor. The hybrid system of vehicle comprises required motor output setting means for setting a required output of the motor depending on a required vehicle driving power, required generator output setting means for setting a required output of the generator depending on the required motor output set by the required motor output setting means, and engine output setting means for setting an output of the engine depending on the required generator output set by the required generator output setting means.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a fundamental configuration of a hybrid system of vehicle according to one embodiment of the present invention.

FIG. 2 is a flowchart showing a direct series control process for the hybrid system of vehicle.

FIG. 3 is a block diagram specifically showing various parameters for use in the direct series control process.

FIG. 4 is a graph having a horizontal axis representing an engine or generator speed, and a vertical axis representing a torque (hereinafter referred to as “equilibrating torque”) at which an engine torque is equilibrated with a generator torque.

FIG. 5 is a flowchart showing a switching control process for a switching element provided between a generator and an electric motor and an internal switch provided between the generator and a battery, in the hybrid system of vehicle.

FIG. 6A is a waveform chart showing a three-phase AC to be generated by the generator, wherein the three-phase AC consists of three sine-waves (U-wave, V-wave, W-wave) having a phase difference of π/3 with respect to each other.

FIG. 6B is a waveform chart showing the U-wave.

FIG. 6C is a waveform chart showing a first example of dividing the U-wave into two components for the motor and the battery.

FIG. 6D is a waveform chart showing a second example of dividing the U-wave into two components for the motor and the battery.

FIG. 6E is a waveform chart showing an example of dividing the U-wave by turning on/off the internal switch while maintaining the switching element in its ON state.

Claims

1. A hybrid system of vehicle designed to drive a generator by an engine and supply an electric power generated by said generator directly to a wheel-driving electric motor so as to drive said motor, comprising: required motor output setting means for setting a required output of said motor depending on a required vehicle driving power;required generator output setting means for setting a required output of said generator depending on said required motor output set by said required motor output setting means; andengine output setting means for setting an output of said engine depending on said required generator output set by said required generator output setting means.

2. The hybrid system of vehicle as defined in claim 1, which further comprises target generator value setting means operable to set a target torque and a target speed of said generator, based on said required generator output set by said required generator output setting means, and wherein after setting a control line which is formed by connecting a part of respective intersection points between a plurality of required motor output lines each representing a change in the required motor output determined using a parameter including a load of said motor, and a high engine efficiency region where a product of a thermal efficiency of said engine and a power generation efficiency of said generator becomes equal to or greater than a given value, in such a manner that each of an engine or generator speed and an equilibrating torque at which an engine torque is equilibrated with a generator torque, becomes higher as the required motor output is increased, the target torque and the target speed of the generator is set based on the required generator output set by the required generator output setting means.

3. The hybrid system of vehicle as defined in claim 2, wherein said target generator value setting means is operable to select maximum efficiency points from respective intersection points between said plurality of required motor output lines and said high engine efficiency region, and connect said selected maximum efficiency points on equi-output lines consisting of said plurality of required motor output lines to form an envelope serving as said control line.

4. The hybrid system of vehicle as defined in claim 2, wherein said target generator value setting means is operable to set said control line to have a portion where the target torque of said generator is rapidly reduced to zero as the engine or generator speed is lowered in a given engine or generator speed region less than those in the high engine efficiency region.

5. The hybrid system of vehicle as defined in claim 2, wherein said target generator value setting means is operable to set said control line to have a portion where the target torque of said generator is rapidly increased as the engine or generator speed is increased in a given equilibrating torque region greater than a maximum equilibrating torque in said high engine efficiency region.

6. The hybrid system of vehicle as defined in claim 1, which further comprises: a battery connected to said generator through an inverter and a converter in this order;first switching means for switching electrical connection between said generator and said battery;second switching means for switching electrical connection between said generator and said motor; andswitching control means for controlling said first and second switching means to allow electric power to be supplied from said battery to said motor and to allow said battery to be charged by said generator.

7. The hybrid system of vehicle as defined in claim 6, wherein said switching control means is operable, when said battery is charged by said generator, to control said first and second switching means in such a manner that said generator is connected to said battery within a given time period around a zero-crossing point along an AC waveform except for positive and negative peak regions in one AC cycle.

8. The hybrid system of vehicle as defined in claim 6, wherein said switching control means is operable, when the electric power is supplied from said battery to said motor at a given value or more, to stop a switching operation of said first and second switching means.

9. A method of controlling a hybrid system of vehicle designed to drive a generator by an engine and supply an electric power generated by said generator directly to a wheel-driving electric motor so as to drive said motor, comprising the steps of: setting a required output of said motor depending on a required vehicle driving power;setting a required output of said generator depending on said required motor output; andsetting an output of said engine depending on said required generator output