Electric Motor PWM Startup Current Control
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Solution Overview
Problem
Electric motors experience high startup currents that can damage batteries and cause dynamic voltage drops, affecting other consumers in vehicles during startup, leading to potential failures.
Innovation Solution
Implementing a method to control electric motor startup currents using high-frequency pulse width modulation (PWM) with a continuous increase limited by a prespecified maximum current gradient, taking into account battery and generator operating parameters, and adjusting rotational speed to prevent current peaks and voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electric motor is started with high startup currents, then the motor can quickly reach operating speed, but current peaks occur that can damage the battery and cause dynamic voltage drops affecting other consumers
Solution Approach 1:
The patent applies dynamics by continuously increasing the motor current from zero to the required operating current rather than applying full current immediately. This dynamic current ramping approach allows the motor to accelerate smoothly while preventing harmful current peaks that would damage the battery or cause voltage drops affecting other electrical consumers in the vehicle.
Solution Approach 2:
The patent changes the current parameter over time by implementing a continuous current increase with a limited current gradient. The control system adjusts the current magnitude dynamically during startup, transitioning from low initial current to full operating current in a controlled manner, thereby resolving the contradiction between fast startup and preventing harmful current peaks.
2Reliability
If the motor current is continuously increased to reach operating current, then the motor can start up, but current peaks can damage the battery
Solution Approach 1:
The patent uses dynamic current control during motor startup, continuously increasing current from zero while limiting the current gradient to prevent harmful peaks. This dynamic approach protects the battery from damage while still achieving motor startup within an acceptable time frame by optimizing the rate of current increase.
Solution Approach 2:
The patent applies preliminary action by pre-limiting the current gradient before harmful current peaks can occur. The control system is configured with predetermined current gradient limits that prevent battery-damaging current spikes from occurring in the first place, ensuring reliable battery protection during the entire startup process.
3Object-affected harmful factors
If the current gradient is limited to a prespecified maximum value, then current peaks are avoided, but the motor startup process takes longer
Solution Approach 1:
The patent optimizes the current parameter by implementing a controlled current gradient that increases continuously from zero to the required operating current. This parameter optimization eliminates harmful current peaks while minimizing startup time by using the maximum safe current gradient, thus resolving the contradiction between peak elimination and startup speed.
4Device complexity
If the battery supplies power to both the electric motor and additional electrical consumers, then energy distribution is simplified, but voltage drops can cause failure of additional consumers during motor startup
Solution Approach 1:
The patent applies dynamics by continuously increasing the motor current from zero with a limited gradient during startup. This dynamic current control prevents sudden current peaks that would cause voltage drops, ensuring that additional electrical consumers connected to the same battery remain operational while maintaining a simple single-battery power supply architecture.
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 prevents battery damage and dynamic voltage drops, ensuring stable power supply to other vehicle consumers by gradually increasing motor current and optimizing energy distribution between batteries and generators.
Implementation Method 1
The electric motor is controlled by pulse width modulation in a direct-voltage network
Data Source
AI summary
A method and a device for controlling and/or regulating an electric motor. Such electric motors are used for example in motor vehicles in the form of pump motors. In general, the electric motor is supplied with electrical energy from a battery and/or using a generator. The controlling and regulation take place using a high-frequency pulse width modulation (PWM). When the electric motor is started, the PWM is used to continuously increase the motor current required for the operation of the electric motor, e.g. beginning from 0.