Brushless DC Motor Stator Coils Series Heating
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Solution Overview
Problem
Brushless DC motors used in conveyor modules for urea and water solutions in SCR systems for diesel engines face limitations in heating power due to low resistance stator coils, which restrict the ability to deliver heating power comparable to reciprocating pumps without risking demagnetization of the rotor.
Innovation Solution
Connecting the stator coils in series during the heating phase increases the total resistance by a factor of 4.5, allowing for a 4.5 times higher heating power while using pulse-width modulation to adapt the heating current based on temperature feedback, and employing MOSFET switches for control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stator coils are connected in parallel (standard delta wiring), then the motor can be triggered with pulse-width-modulated voltage, but the heating power is insufficient (only 1.32 watts at 2 amps)
Solution Approach 1:
The patent applies dynamics by making the circuit configuration changeable between parallel (for motor operation) and series (for heating operation). The control device dynamically switches between these two connection modes depending on whether the brushless DC motor is being used for propulsion or for heating the urea solution, allowing the system to optimize its electrical configuration for each specific function.
Solution Approach 2:
The patent changes the electrical resistance parameter of the stator coil circuit by switching between parallel and series connections. In parallel connection, the resistance is low (0.33 ohms) enabling PWM triggering; in series connection, the resistance increases (1.5 ohms) enabling high heating power (6.75 watts at 2.12 amps) without demagnetizing the rotor.
2Power
If the current through the stator coils is increased to deliver higher heating power, then the heating effectiveness improves, but the strong magnetic field may demagnetize the permanent magnets of the rotor
Solution Approach 1:
The patent changes the circuit configuration from parallel to series connection, which increases the electrical resistance by a factor of 4.5. This allows the system to deliver higher heating power (6.75 watts vs 1.32 watts at 2 amps) while maintaining the same current level, thereby avoiding the demagnetization risk that would occur with higher current in parallel connection.
3Power
If the stator coils are connected in series, then the heating power increases by a factor of 4.5, but the motor cannot be triggered with pulse-width modulation
Solution Approach 1:
The patent implements dynamic switching between two operational modes: motor mode with parallel connection for PWM triggering, and heating mode with series connection for high heating power. The control device automatically selects the appropriate connection configuration based on the operational requirement, ensuring both motor functionality and heating effectiveness are preserved at different times.
4Power
If a separate heating unit is installed in the hydraulic duct system, then the heating effectiveness improves, but the system cost increases
Solution Approach 1:
The patent makes the stator coils universal by enabling them to perform both motor function (when connected in parallel) and heating function (when connected in series). This eliminates the need for a separate heating unit in the hydraulic duct system, as the existing motor components can fulfill both propulsion and heating requirements, thereby reducing system cost and complexity.
Solution Approach 2:
The patent enables the brushless DC motor to serve itself by using its own stator coils for both motor operation and heating the urea solution. The motor components provide the heating function that would otherwise require separate dedicated heating equipment, making the system self-sufficient and cost-effective.
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 enhances the heating power of brushless DC motors by a factor of 4.5 compared to standard delta wiring, ensuring efficient heating of the urea and water solution without excessive system temperatures or demagnetization risks, thus improving the efficiency and durability of the conveyor module.
Implementation Method 1
stator coils of the brushless DC motor have an electric voltage applied to them during a heating phase
Data Source
AI summary
The invention relates to a method for heating a device driven with a brushless direct current motor, in which method a voltage is applied to stator coils of the brushless direct current motor during a heating phase. The invention further relates to a device for carrying out said method. According to the invention, the stator coils are series-connected during the heating phase. The series connection of the stator coils increases the resistance by a factor of 4.5 compared to a parallel connection of a stator coil with a series connection of two stator coils, as occurs in a brushless direct current motor wired according to the prior art. The heating power is therefore also higher by a factor of 4.5 with the same operating current.