Hybrid Vehicle Power Control Unit Feedforward Voltage Stability
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Solution Overview
Problem
Traditional power system architectures for hybrid electric vehicles face inefficiencies due to communication delays and the need for brake resistors to manage voltage transients, leading to increased cost, weight, and complexity, as well as power loss during braking and motoring operations.
Innovation Solution
A power control unit with collocated vehicle power management circuitry, generator inverter, motor inverter, and bi-directional DC-to-DC converter enables feedforward control, predicting and managing current influx or draw to maintain DC bus voltage stability without the need for brake resistors, thereby improving vehicle dynamics and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional power system architecture uses brake resistor to manage voltage transients, then DC bus voltage stability is maintained, but vehicle cost, weight, and complexity increase
Solution Approach 1:
The patent removes the brake resistor from the power system architecture by implementing a control strategy that directs regenerative braking energy flow to the battery through coordinated control of the motor inverter and DC-DC converter, eliminating the need for energy dissipation components and reducing system complexity
Solution Approach 2:
The patent employs feedforward control that predicts current influx during braking events and pre-adjusts the operation of the DC-DC converter and battery charging parameters before voltage transients occur, preventing over-voltage conditions without requiring brake resistors
2Stability of the object's composition
If brake resistor is used to absorb excess voltage transients, then DC bus voltage is maintained within range, but power loss occurs during braking
Solution Approach 1:
The patent converts the harmful effect of regenerative braking (voltage transients) into a beneficial outcome by capturing the excess electrical energy generated during braking and directing it to charge the battery, transforming what would be wasted energy into useful stored energy for later use
Solution Approach 2:
Instead of discarding braking energy through resistive dissipation, the patent recovers the electrical energy generated during regenerative braking by controlling the motor inverter and DC-DC converter to transfer energy to the battery, maximizing energy utilization
3Stability of the object's composition
If traditional power system architecture responds to voltage transients, then system reacts to maintain stability, but response time is insufficient for desired vehicle dynamics
Solution Approach 1:
The patent implements feedforward control that predicts current influx during braking events based on driver input and vehicle state, and pre-adjusts the DC-DC converter operation and battery charging parameters before voltage transients occur, achieving faster response than traditional feedback control
Solution Approach 2:
The patent merges the control functions of the motor inverter and DC-DC converter into a coordinated control system managed by a single controller, enabling seamless energy management and faster response to braking events by eliminating communication delays between separate control systems
4Measurement precision
If communication delays exist in traditional power system architecture, then control accuracy is reduced, but system complexity increases
Solution Approach 1:
The patent consolidates the control of the motor inverter, generator inverter, and DC-DC converter into a single integrated control system, eliminating communication delays between separate controllers and improving coordination accuracy for energy management during transient events
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 solution reduces communication delays, eliminates the need for brake resistors, and enhances overall vehicle efficiency by allowing complete recapture of braking currents and improved responsiveness during dynamic operations.
Implementation Method 1
an expected amount of charging current to a battery via the DC-to-DC converter
Implementation Method 2
The generator converts mechanical energy from the engine into electric energy on the DC bus via an inverter in a generation mode
Implementation Method 3
The traction motor converts electric energy from the DC bus into mechanical energy via an inverter for use in driving one or more traction elements
Data Source
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AI summary
An improved power system architecture for a hybrid electric vehicle includes a power control unit including a motor inverter, a generator inverter, and a DC-to-DC converter, and vehicle power management (VPM) circuitry directly connected to each of the motor inverter, generator inverter, and DC-to-DC converter. In this arrangement, communication timing is greatly reduced, thereby allowing for feedforward control of the motor inverter, generator inverter, and DC-to-DC converter. The feedforward control enables the VPM circuitry to predict current influx or draw by a motor and determine the corresponding currents to provide to or from the generator and battery prior to or simultaneously with the actual current influx or draw by the motor. This improves vehicle dynamics and responsiveness, as well as enables complete recapture of braking currents and eliminates the need for a brake chopper resistor, thereby improving overall vehicle efficiency.