Motor Drive Device Switching Circuit for Full Battery Braking
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Solution Overview
Problem
Existing motor drive systems for electric vehicles face challenges when batteries are fully charged, as regenerative braking is no longer possible, leading to increased heat and wear from mechanical brakes, especially when driving down slopes, and require larger brake units and heat removal structures.
Innovation Solution
A motor drive device with a switchable circuit configuration that allows for regenerative braking, short-circuit braking, and resistor braking, controlled by a regenerative braking and short-circuit braking switching controller, enabling braking operations even when batteries are fully charged, and allowing for the use of smaller mechanical brakes or their omission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is used to recover kinetic energy when the battery is fully charged, then power can be stored in the battery, but when the battery is fully charged, regenerative braking is no longer possible and mechanical brakes must be used which generate large heat
Solution Approach 1:
The patent converts the harmful effect of kinetic energy that cannot be stored (when battery is full) into a useful braking force. By short-circuiting the motor coils, the generated electricity during braking is dissipated as heat within the motor itself, creating a beneficial braking effect without requiring mechanical brakes or external resistors.
Solution Approach 2:
The patent replaces the mechanical brake system with an electrical braking system. Instead of using friction-based mechanical brakes to stop the vehicle, the motor's electromagnetic properties are utilized through short-circuit braking, substituting mechanical energy dissipation with electrical energy dissipation within the motor coils.
2Ease of operation
If a resistor is used to dissipate power generated by the motor to perform braking operation, then braking can be achieved, but a resistor of significant size is necessary to produce sufficient braking torque, making this an impractical way
Solution Approach 1:
The patent makes the motor unit serve multiple functions: it can act as both a drive motor and a braking device. By short-circuiting the motor coils, the motor itself becomes the braking mechanism, eliminating the need for separate resistors or heat removal structures. The motor's electromagnetic properties are utilized for both propulsion and braking.
Solution Approach 2:
The motor unit performs braking operation on its own without requiring external components. The short-circuit braking mechanism uses the motor's own coils and electromagnetic properties to generate braking force, making the system self-sufficient for braking operations without needing separate resistors or cooling systems.
3Adaptability or versatility
If motor coils are short-circuited to create braking force, then braking operation can be performed without mechanical brakes, but merely short-circuiting the motor coils may result in the generation of excessively large braking torque, leading to abrupt braking
Solution Approach 1:
The patent introduces dynamic control of the short-circuit braking process. The connection configuration is switchable, allowing the system to transition between drive mode, regenerative braking mode, and short-circuit braking mode. The short-circuit current controller dynamically adjusts the braking torque to match required levels, preventing abrupt braking while maintaining flexibility.
Solution Approach 2:
The patent implements feedback control through the short-circuit current controller and regenerative braking switching controller. These controllers monitor the braking conditions and adjust the short-circuit current accordingly, comparing actual braking torque with required torque to achieve smooth and controlled braking without excessive force.
4Temperature
If mechanical brake units are made larger to handle heat from prolonged use, then heat dissipation capability is improved, but the device size and complexity increase
Solution Approach 1:
The patent replaces the mechanical brake heat dissipation system with an electrical short-circuit braking system. Instead of enlarging mechanical brakes and heat removal structures, the system uses the motor's electromagnetic properties to convert kinetic energy directly into electrical energy that is dissipated within the motor coils, eliminating the need for large mechanical brake components.
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 enables efficient braking operations without the need for large mechanical brakes or heat removal structures, reducing heat generation and wear, and allows for the use of smaller mechanical brakes, thereby enhancing the performance and durability of electric vehicles.
Implementation Method 1
motor coils of the motor unit 6 to short-circuit to create a braking force
Implementation Method 2
power generated by the motor unit 6 during a regenerative braking operation to be used to charge the battery unit 19
Data Source
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AI summary
A motor drive device (20) includes a circuit (31) (e.g., an inverter) with a connection configuration that is switchable among: (a) a drive operative connection configuration that allows a motor unit (6) to be driven with power supplied from a battery unit; (b) a regenerative braking connection configuration; and (c) a short-circuit connection configuration that causes motor coils of the motor unit (6) to short-circuit to create a braking force. The motor drive device (20) also includes a short-circuit current controller (26) configured to control a short-circuit current that flows when the connection configuration of the circuit is (c) the short-circuit connection configuration. The motor drive device (20) also includes a regenerative braking and short-circuit braking switching controller (25) that may cause switching from (b) the regenerative braking connection configuration to (c) the short-circuit connection configuration, or vise versa.