DC Motor Start-Up PWM Switching for Peak Current Reduction
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Solution Overview
Problem
Brushed DC motors experience high peak start-up currents, leading to increased costs due to the need for high-quality components and a risk of component burning during long-term use, necessitating a reduction in start-up current.
Innovation Solution
A start-up device for DC motors that includes a switching element connected in series with the motor and power supply, controlled by a unit that periodically switches between ON and OFF states using pulse width modulation (PWM) to reduce peak start-up current, and maintains the ON state after a predetermined interval, optionally with overcurrent protection and electromagnetic pulse absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-quality electronic components are used to handle high start-up current, then reliability is improved, but product cost increases
Solution Approach 1:
The patent applies periodic switching action through PWM control during motor start-up. The switching element periodically switches between ON and OFF states in a predetermined time interval, creating a pulsed current profile that reduces the peak start-up current while maintaining the motor's ability to start. This periodic action allows the use of lower-rated, less expensive components while achieving the same reliability goal.
2Reliability
If high-quality electronic components are used to handle high start-up current, then component durability is improved, but device complexity increases
Solution Approach 1:
The control unit implements periodic switching control during a predetermined start-up time interval, causing the switching element to alternate between ON and OFF states. This time-limited periodic control simplifies the overall circuit design compared to using continuously rated high-power components, as the switching element only needs to handle peak currents temporarily during start-up rather than continuously.
3Reliability
If PWM switching is used to reduce peak start-up current, then component stress is reduced, but control complexity increases
Solution Approach 1:
The control unit generates PWM signals that periodically switch the switching element during a predetermined time interval T. This time-limited periodic control reduces component stress by avoiding continuous high-current conditions, while the control complexity is managed by confining the PWM operation to only the start-up phase rather than continuous operation.
Solution Approach 2:
The patent changes the electrical parameters (current waveform, switching frequency, duty cycle) during the motor start-up period by applying PWM control. These parameter changes allow the system to reduce peak current and component stress during the critical start-up phase, while returning to normal parameters once the motor is running, thereby balancing stress reduction with acceptable control complexity.
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 solution effectively reduces peak start-up currents, minimizing component stress and costs by controlling the switching element's state with PWM, ensuring lower peak currents and prolonged component lifespan.
Implementation Method 1
a control unit configured to cause the switching element to periodically switch between an ON state and an OFF state in a predetermined time interval to reduce a peak value of a start-up current flowing through the DC motor
Implementation Method 2
a capacitor connected between positive and negative terminals of the DC motor to absorb electromagnetic pulse components generated by the DC motor
Data Source
AI summary
The present application relates to a motor control technology, and in particular to a start-up device for a DC motor, a motor system comprising the start-up device, a method for reducing DC motor start-up current and a computer-readable storage medium with a computer program stored thereon for implementing the above method. The start-up device for a DC motor according to one aspect of the present application includes: a switching element connected in series within a circuit comprising the DC motor and a DC power supply; and a control unit configured to cause the switching element to periodically switch between an ON state and an OFF state in a predetermined time interval to reduce the peak value of a start-up current flowing through the DC motor, and to cause the switching element to maintain the ON state after the predetermined time interval ends.