Inductive Load Drive Control via Variable PWM Frequency
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Solution Overview
Problem
Conventional drive control systems for inductive loads, such as solenoid actuators in automatic transmissions, face challenges in controlling current ripple amounts and sliding resistance, leading to increased manufacturing costs and inefficiencies due to the need for customized average current detecting circuits for different inductive loads.
Innovation Solution
A drive control apparatus that adjusts the pulse width and fluctuation period of the PWM control to match a reference current value, ensuring the current ripple falls within a detectable range, thereby minimizing sliding resistance and reducing the need for load-specific circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the current ripple amount is increased to minimize sliding resistance of the linear solenoid, then the sliding resistance is reduced, but the current ripple exceeds the detectable range of the average current detecting circuit
Solution Approach 1:
The patent applies dynamics by making the PWM frequency variable rather than fixed. The control device adjusts the PWM frequency dynamically based on the detected average current value, allowing the system to optimize current ripple characteristics for different operating conditions while keeping the ripple within the detectable range of the fixed-bandwidth detecting circuit.
Solution Approach 2:
The patent changes the PWM frequency parameter adaptively. When the average current value changes, the control device modifies the PWM frequency to maintain optimal current ripple amplitude. This parameter change ensures that the current ripple remains within the detectable range of the average current detecting circuit while still achieving minimal sliding resistance.
2Measurement precision
If customized average current detecting circuits are designed for different inductive loads to accommodate varying current ripple amounts, then the measurement precision is improved, but the device complexity and manufacturing costs increase
Solution Approach 1:
The patent achieves universality by designing a single average current detecting circuit with fixed bandwidth that can serve multiple different inductive loads. The control device adapts the PWM frequency to match the characteristics of each load, allowing one detecting circuit to handle various loads without customization, thereby reducing device complexity and manufacturing costs.
Solution Approach 2:
Instead of customizing the detecting circuit for each load, the patent changes the PWM frequency parameter to adapt to different load characteristics. This approach allows a universal detecting circuit to maintain measurement precision across different inductive loads by adjusting the excitation frequency rather than the detection hardware.
3Measurement precision
If the PWM frequency is increased to reduce current ripple amount, then the measurement precision is improved, but the sliding resistance of the linear solenoid increases
Solution Approach 1:
The patent optimizes the PWM frequency parameter to achieve a balance between current ripple detection and sliding resistance minimization. Rather than simply increasing or decreasing the frequency, the control device selects an optimal frequency range that maintains current ripple within the detectable range while minimizing sliding resistance through adaptive frequency adjustment.
Solution Approach 2:
The patent employs feedback by using the output from the average current detecting circuit to adjust the PWM frequency. The control device continuously monitors the average current value and modifies the PWM frequency accordingly, creating a closed-loop system that optimizes both measurement precision and sliding resistance performance.
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 allows for reduced sliding resistance and adaptable current ripple control across various inductive loads on a single circuit, enhancing efficiency and cost-effectiveness by maintaining current ripple within detectable ranges without requiring extensive customization.
Implementation Method 1
the current flowing through the inductive load is controlled by pulse width modulation (hereinafter referred to as 'PWM')
Implementation Method 2
inductive load such as a solenoid actuator used in automatic transmissions for automobiles
Data Source
AI summary
A drive control apparatus controls a drive of an inductive load having a current flowing therethrough. The drive control apparatus includes a drive control device for controlling a variation of the current flowing through the inductive load within a certain period by Pulse Width Modulation control so as to come close to a reference current value, and a reference value control device for controlling a fluctuation period of the reference current value and making the fluctuation period of the reference current value longer than that of the current flowing through the inductive load by the Pulse Width Modulation control.