Hybrid Vehicle Inverterless Control Using Estimated Rotation Speed
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Solution Overview
Problem
During inverterless running control in hybrid vehicles, the rotation speed of the first rotating electric machine can exceed predetermined limits due to the inability of the control device to obtain output values from sensors, leading to potential overheating or overrevolution of the machine.
Innovation Solution
The implementation of a controller that calculates estimated rotation speeds of the first rotating electric machine based on engine and wheel speed sensors' data, allowing for the control of engine rotation speed to keep the machine within a predetermined speed region, even when sensor outputs are unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control device cannot obtain output values from the first sensor and second sensor during inverterless running control, then the rotation speed of the first rotating electric machine cannot be monitored, but this leads to overspeed rotation exceeding the predetermined rotation speed region
Solution Approach 1:
The patent introduces an intermediary calculation method using engine rotation speed and wheel rotation speed as mediators to estimate the first rotating electric machine's speed when direct sensors fail. The controller calculates estimated speed values based on the relationship between engine speed, wheel speed, and planetary gear ratios, serving as a backup measurement pathway when primary sensors are unavailable.
Solution Approach 2:
The patent creates a virtual copy of the speed detection function by calculating estimated speed values from other available sensor data. Instead of relying solely on the first sensor for direct measurement, the system replicates the speed monitoring function through computational estimation using engine rotation speed sensor and wheel rotation speed sensor data.
2Reliability
If the rotation speed of the first rotating electric machine is suppressed to be within a predetermined rotation speed region, then overheating and overrevolution are prevented, but this requires strict vehicle speed restrictions
Solution Approach 1:
The patent implements dynamic speed restriction adjustment based on the availability of sensor data. When the first sensor and second sensor are functioning normally, the system applies standard speed restrictions. When these sensors fail, the system dynamically adjusts the restriction strategy by using calculated estimated values, allowing for relaxed vehicle speed restrictions while still preventing overspeed rotation through engine rotation speed control.
Solution Approach 2:
The patent changes the control parameter from direct speed measurement to estimated speed calculation when sensor data is unavailable. By switching between direct sensor readings and calculated estimated values, the system maintains appropriate speed restrictions while adapting to different sensor availability conditions, thereby improving ease of operation without compromising safety.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses overspeed rotation of the first rotating electric machine, preventing secondary failures such as overheating and overrevolution, while allowing for relaxed vehicle speed restrictions when the direction of travel can be determined.
Implementation Method 1
During inverterless running control, a counter-electromotive voltage is generated in the first rotating electric machine by dynamically (mechanically) rotating the first rotating electric machine with rotational force of the engine. When a current flows from the first rotating electric machine to the battery with the counter-electromotive voltage, counter-electromotive torque (braking torque) applied in a direction interfering rotation of the first rotating electric machine is generated in the first rotating electric machine.
Implementation Method 2
When the controller cannot obtain output values from the first sensor and the second sensor during the inverterless running control, the controller is configured to calculate a first estimated value of a rotation speed of the first rotating electric machine at the time when the wheel is assumed to rotate forward and a second estimated value of a rotation speed of the first rotating electric machine at the time when the wheel is assumed to rotate rearward, by using an output value from the engine rotation speed sensor and an output value from the wheel speed sensor.
Data Source
AI summary
An ECU performs control processing including setting an inverter to a gate blocking state when an abnormal condition of the inverter occurs, activating a converter, driving an engine, carrying out first suppression control when an abnormal condition of a resolver occurs and when an MG2 rotation speed immediately before occurrence of the abnormal condition is equal to or smaller than a first speed threshold value, and carrying out second suppression control when the MG2 rotation speed immediately before occurrence of the abnormal condition is greater than the first speed threshold value and when there is no record of stop.