Motor Drive Control Device Using Relay H-Bridge Switching Sequence
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Solution Overview
Problem
The complexity and high cost of controlling motors using typical H-bridge inverters, along with the risk of spark-induced damage to mechanical switches and neighboring circuits when using relay switches, due to the need to manage four active switches and the occurrence of voltage chattering during switching.
Innovation Solution
A motor drive control device employing two relay switching units in an H-bridge configuration, controlled by an inverter controller that sequences the switching to protect the relay switches and minimize voltage chattering by ensuring the relay contacts are switched after the motor winding current reaches zero, thereby preventing damage and reducing system complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If mechanical switches (relays) are used in H-bridge inverter to reduce cost, then device complexity and cost are reduced, but spark occurs during switching which reduces switch life and damages neighboring circuits
Solution Approach 1:
The inverter controller performs preliminary action by controlling the switching unit to disconnect the voltage source before controlling the relay switching unit to switch contacts. This sequencing prevents spark occurrence when relay contacts close, thereby extending switch life and preventing damage to neighboring circuits while maintaining the cost benefits of using mechanical relays.
2Adaptability or versatility
If four active switches are controlled in typical H-bridge inverter, then motor can be driven in both directions, but control complexity increases and system cost increases
Solution Approach 1:
The invention merges the functions of four separate active switches into a single switching unit that controls voltage source connection. Combined with two relay switching units that handle contact switching, this reduces the number of independently controlled switching elements from four to three (one power switch + two relay controls), thereby reducing control complexity while maintaining bidirectional motor control capability through the H-bridge configuration.
3Productivity
If relay contacts are switched during motor operation, then voltage chattering occurs which damages relay switches and causes harmful effects
Solution Approach 1:
The inverter controller uses feedback by monitoring motor operation state to determine the appropriate timing for relay contact switching. By controlling the switching unit to disconnect voltage before relay contacts switch, and by controlling relays to open contacts only after voltage disconnection, the system prevents voltage chattering that would otherwise occur during relay switching while the motor is running, thereby eliminating harmful effects.
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 protects relay switches from damage and minimizes voltage chattering during switching operations, simplifying the control system and reducing costs by sequencing the voltage supply and disconnection to prevent relay contact wear and spark-induced issues.
Implementation Method 1
two relay switching units which are coupled to both sides of a motor and each of which is formed in an H-bridge shape
Implementation Method 2
a switching unit which controls a voltage source applied to the relay switching units
Implementation Method 3
a motor (M) rotates in the right or reverse direction according to the polarity of voltage applied to the motor
Data Source
AI summary
Disclosed is a motor drive control device which uses mechanical switches configured in an H-bridge shape and can protect the mechanical switches from being damaged and minimize a voltage chattering problem occurring upon switching on and off The motor drive control device includes: two relay switching units which are coupled to both sides of a motor and each of which is formed in an H-bridge shape and is connected to an output terminal of a bridge circuit; a switching unit which controls a voltage source applied to the relay switching units; and an inverter controller which first controls any one of the relay switching units and then controls the switching unit so that the motor starts to operate, and first controls the switching unit and then controls the one of the relay switching units so that the motor comes to a halt.