H-Bridge Drive Heating via Circulating Phase Currents
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Solution Overview
Problem
Existing drive devices face challenges in creating sufficient heat to effectively warm energy storage devices at low temperatures, particularly in vehicles like battery electric vehicles, where hydraulic oil temperature is below a predetermined level.
Innovation Solution
A drive device configuration with a three-phase coil motor, two inverters in an H-bridge setup, and a cooling system, controlled to maximize current flow through the motor and inverters to generate heat, using feedback control to manage phase and zero-phase currents based on heat requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the motor and inverters operate at low temperatures, then the energy storage device can be heated, but the amount of heat generated is insufficient to effectively raise the temperature
Solution Approach 1:
Instead of allowing current to flow directly through the energy storage device, the patent inverts the path by routing current through the motor and inverters first. The control device directs current from the power line through the first inverter, then through the motor, then through the second inverter, and finally back to the power line, generating heat in these components which indirectly heats the energy storage device.
Solution Approach 2:
The motor and inverters serve as intermediary components that generate heat. Rather than directly heating the energy storage device, the system uses the motor and inverters as mediators that convert electrical energy to thermal energy, which then transfers to the energy storage device through thermal coupling in the common cooling system.
2Power
If larger current flows through the motor and inverters to generate more heat, then heat generation increases, but the system complexity increases due to control requirements
Solution Approach 1:
The control device performs multiple functions: it controls the switching of the first and second inverters, regulates current flow through the motor, monitors temperature conditions, and manages the heating process. This multi-functionality reduces the need for separate dedicated control components, thereby managing complexity while achieving the desired heat generation.
Solution Approach 2:
The control device implements feedback control by monitoring the temperature of the energy storage device and adjusting the current flow through the motor and inverters accordingly. The control device determines when to start and stop the heating process based on temperature thresholds, creating a closed-loop system that automatically regulates heat generation without requiring complex manual control.
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 configuration allows for increased heat generation, effectively raising the temperature of the energy storage device and reducing degradation due to low temperatures, enhancing performance and reliability.
Implementation Method 1
a larger amount of heat can be created by the motor and the first and second inverters
Implementation Method 2
a cooling device configured to cool the energy storage device, the motor, the first inverter, and the second inverter using a cooling medium
Data Source
AI summary
A drive device includes: an energy storage device; a motor including a three-phase coil; a first inverter including multiple first switching elements and connected to a power line to which the energy storage device is connected, and to a first end of the three-phase coil; a second inverter including multiple second switching elements and connected to the power line and a second end of the three-phase coil; a cooling device that cools the energy storage device, the motor, and the first and second inverters using a cooling medium; and a control device that controls the first and second inverters based on a torque command from the motor. The control device controls the first and second inverters such that all phase currents of three phases of the three-phase coil circulate from one of the first and second inverters to the three phases via the power line and the other inverter.