Motors and Control

Understanding Relay Coil Voltage Requirements Relays contain an electromagnet that is energized by applying voltage across its coil terminals. This creates a magnetic field that actuates the relay’s mechanical switch contacts. Always-on relays require the coil voltage to be maintained steadily within the pickup and dropout voltage range specified by the manufacturer in order for…

Understanding Relay Triggering Mechanisms Electromagnetic Relays Electromagnetic relays contain a coil that activates an electromagnet when current flows through it. The electromagnet generates a magnetic field that pulls a contact armature and switches the relay contacts. The coil current can be controlled from a microcontroller by toggling a digital output pin high or low. Example…

What is an H-Bridge? An H-bridge is an electronic circuit that enables voltage to be applied across a load, such as a motor, in either direction. It contains four switching elements, such as transistors or relays, that are arranged in a bridge configuration to allow current to flow through the motor in both directions, allowing…

Core Issue: Voltage Drop Across Power Devices The core technical issue in H-bridge motor drivers that influences voltage regulation is the unavoidable voltage drop that occurs across the power devices during current flow. This voltage drop is described by Ohm’s law as: Voltage Drop = Load Current x On-State Resistance of Power Devices This voltage…