Relay Drive Unit PWM Duty Ratio Voltage Detection
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Solution Overview
Problem
Existing relay drive units for in-vehicle electronic control units have increased production costs due to separate coil voltage detection circuits and complex constant voltage maintenance circuits, leading to higher production costs and complexity.
Innovation Solution
A relay drive unit that includes a power source voltage detector, a drive signal generator, and a relay drive circuit, which generates a PWM signal with a preset duty ratio based on detected power source voltage to maintain the relay in an ON state, reducing the need for continuous power supply and simplifying voltage maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate coil voltage detecting circuit is used to detect the voltage between terminals of the relay coil, then the relay operation can be maintained stable, but the production cost of the relay drive unit is increased
Solution Approach 1:
The patent combines the voltage detection function and relay drive function into a single integrated circuit. The microcontroller unit (MCU) integrates both the analog-to-digital converter (ADC) for voltage detection and the PWM generation capability for relay drive, eliminating the need for separate detection circuits and reducing production costs while maintaining reliable operation.
2Reliability
If a complex constant voltage power circuit is used to generate constant voltage for keeping relay contact in ON state, then the relay can be kept in ON state with stable voltage, but the circuit complexity and production cost are increased
Solution Approach 1:
The patent employs PWM (pulse width modulation) technique to maintain the relay in ON state. Instead of using a complex constant voltage circuit, the system generates periodic PWM signals with adjusted duty ratios that deliver the required average power to the relay coil, keeping it energized reliably while simplifying the circuit architecture.
Solution Approach 2:
The system dynamically adjusts the PWM duty ratio based on the detected battery voltage to maintain stable relay operation. When battery voltage fluctuates, the MCU modifies the PWM duty cycle in real-time, allowing the relay to remain in ON state under varying voltage conditions without requiring a complex constant voltage regulation circuit.
3Reliability
If the duty ratio of PWM signal is adjusted according to coil voltage to keep electric current stable, then the relay remains in ON state, but requires continuous monitoring and adjustment increasing system complexity
Solution Approach 1:
The microcontroller unit serves multiple functions: it detects battery voltage through the ADC, determines the appropriate PWM duty ratio based on detected voltage levels, generates the PWM signal, and drives the relay. This multi-functional integration eliminates the need for separate monitoring and adjustment circuits, reducing overall system complexity while maintaining stable relay operation.
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 solution stabilizes relay operation by adjusting the PWM signal duty ratio in response to power source voltage changes, maintaining the relay ON state with reduced power consumption and without the need for complex circuitry, thereby lowering production costs and ensuring continuous relay operation.
Implementation Method 1
a power source voltage detector that detects the power source voltage
Implementation Method 2
The drive signal generator generates a PWM signal as a drive signal for maintaining the relay in an ON state. The drive signal has a preset duty ratio according to a magnitude of the power source voltage
Data Source
AI summary
A relay drive unit drives a relay by supplying a power source voltage from a battery. The relay drive unit includes a power source voltage detector, a drive signal generator, and a relay drive circuit. The power source voltage detector detects the power source voltage. The drive signal generator generates a PWM signal as a drive signal for maintaining the relay in an ON state. The PWM signal has a preset duty ratio according to a magnitude of the power source voltage detected by the power source voltage detector. The relay drive circuit turns a supply of the power source voltage from the battery on/off based on a duty ratio of the drive signal generated by the drive signal generator.