Dual-Motor Hybrid Powertrain Bus Voltage Switching for EV Torque
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Solution Overview
Problem
Existing electric vehicle motor control systems face challenges in efficiently managing torque output and energy recovery, particularly when the battery state of charge is low, leading to increased costs, volume, and heat due to the need for bidirectional DC-DC conversion circuits.
Innovation Solution
A hybrid powertrain system that includes a generator, a motor, a dual-motor controller, and a switch module, where the dual-motor controller has a generator power circuit and a motor power circuit, and the switch module adjusts its connection based on the vehicle's running status to form different circuits, thereby adjusting the bus capacitor voltage and adapting to various operating scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a bidirectional DC-DC conversion circuit is used to increase bus voltage and enhance torque output capability, then the torque output capability and running efficiency are improved, but costs, volume, and heat generation increase
Solution Approach 1:
The patent merges the DC-DC conversion function with the existing motor controller by utilizing the motor controller's switching transistors and circuit structure. The switch module integrates the bidirectional DC-DC conversion circuit into the motor controller framework, allowing one component to perform multiple functions (motor control and voltage conversion), thereby reducing overall system complexity while maintaining enhanced torque output capability
Solution Approach 2:
The motor controller is designed to serve dual purposes: conventional motor control and bidirectional DC-DC voltage conversion. The switching transistors and circuit architecture are configured to perform both motor drive functions and voltage boosting/conversion functions, eliminating the need for a separate dedicated DC-DC conversion circuit and reducing system volume and cost
2Use of energy by moving object
If a bidirectional DC-DC conversion circuit is added to manage voltage and energy recovery, then energy recovery capability is improved, but occupied space and costs increase
Solution Approach 1:
The energy recovery function is merged into the motor controller structure. During regenerative braking, the motor acts as a generator and the motor controller's switching circuitry performs the rectification and voltage regulation functions that would otherwise require a separate DC-DC converter, thereby enabling energy recovery without increasing occupied space
Solution Approach 2:
The motor controller is designed to handle multiple energy management functions including motor drive, regenerative braking energy recovery, and bidirectional voltage conversion. This multi-functional design allows the system to recover energy during braking while using the same circuit components, thus improving energy recovery capability without additional space requirements
3Productivity
If a bidirectional DC-DC conversion circuit is used to enhance torque output, then running efficiency is improved, but heat generation increases
Solution Approach 1:
The DC-DC conversion function is combined with the motor controller, allowing heat generated during voltage conversion to be dissipated through the motor controller's existing thermal management pathways. This integration enables efficient torque output enhancement while utilizing the same thermal management infrastructure, thereby reducing overall heat generation issues
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
The proposed solution reduces costs and occupied space, decreases heat generation, enhances the running efficiency and torque output capability of the drive motor, and increases the endurance capability of electric vehicles by effectively managing voltage and energy distribution.
Implementation Method 1
a running status of the switch module includes a first state and a second state, where if the switch module is in the first state, the switch module is configured to connect to an end of a power battery and a center tap of the multiphase winding of the motor; or if the switch module is in the second state, the switch module is configured to connect to an end of a power battery and an end of the plurality of switching transistor bridge arms of the motor power circuit
Implementation Method 2
the multiphase winding and the plurality of switching transistor bridge arms form a voltage conversion circuit. According to the hybrid powertrain provided in this application, in a scenario in which the motor rotates with the wheels, the switch module is in the first state, so that the multiphase winding and the plurality of switching transistor bridge arms form the voltage conversion circuit, to adjust the voltage between the two ends of the bus capacitor
Implementation Method 3
bridge arm midpoints of a plurality of switching transistor bridge arms of the motor power circuit are configured to connect to a multiphase winding of the motor
Implementation Method 4
bridge arm midpoints of a plurality of switching transistor bridge arms of the generator power circuit are configured to connect to a multiphase winding of the generator
Data Source
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AI summary
This application provides a hybrid powertrain (102) for an electric vehicle. The hybrid powertrain (102) includes a generator (13), a motor (12), a dual-motor controller (120a,130a), and a switch module (S). The dual-motor controller (120a,130a) includes a generator power circuit (130a) and a motor power circuit (120a). A running status of the switch module (S) includes a first state and a second state. If the switch module (S) is in the first state, the switch module (S) is configured to connect to an end of a power battery (20) and a center tap of a multiphase winding of the motor (12). If the switch module (S) is in the second state, the switch module (S) is configured to connect to an end of a power battery (20) and an end of a plurality of switching transistor bridge arms of the motor power circuit (120a). This application further provides a control apparatus (103). The control apparatus (103) is configured to control, based on a working status of a powertrain (101), a hybrid powertrain (102) to adjust a voltage between two ends of a bus capacitor (Cbus1). According to the hybrid powertrain (102) and the control apparatus (103) provided in this application, running efficiency and a torque output capability of a motor (12) can be improved, thereby improving entire vehicle endurance and power performance of the electric vehicle.