Motor Drive Device PWM to Linear Switching Control
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Solution Overview
Problem
Motor drive systems experience unnecessary energy loss due to improper switch timing between PWM and linear drive states, leading to glitches and flow-through currents in the output current.
Innovation Solution
A motor drive device with a control circuit that manages the switching between PWM and linear drive states by temporarily setting the driver circuit to an output high impedance state, ensuring the path of the output current does not change during the transition, thereby preventing energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the motor drive system switches between PWM and linear drive states without considering switch timing, then the motor can operate in both drive modes, but glitches and flow-through currents occur in the output current causing unnecessary energy loss
Solution Approach 1:
The control circuit temporarily sets the driver circuit to an output high impedance state before switching from PWM to linear drive mode. This preliminary action prepares the circuit by disconnecting the PWM drive path in advance, ensuring that no flow-through current occurs during the transition and eliminating energy loss associated with improper switching.
2Ease of operation
If the driver circuit switches from PWM to linear drive state without temporary high impedance state, then the switching operation is simple, but flow-through current flows to power amplifier output stage causing unnecessary energy loss
Solution Approach 1:
The output high impedance state serves as an intermediary condition between PWM and linear drive modes. By introducing this intermediate state, the circuit smoothly transitions between drive modes without direct switching that would cause flow-through current. The high impedance state acts as a buffer that prevents harmful current flow while maintaining operational simplicity through automated control.
3Adaptability or versatility
If the switch timing from PWM to linear drive system is not optimized, then the motor drive system can switch between modes, but the path of output current changes during switching causing glitches and energy loss
Solution Approach 1:
The control circuit temporarily sets the driver circuit to an output high impedance state before switching from PWM to linear drive mode. This preliminary action prepares the circuit by disconnecting the PWM drive path in advance, ensuring that no flow-through current occurs during the transition and eliminating energy loss associated with improper switching.
Data Source
AI summary
A motor drive device has a driver circuit generating an output current for a motor and a control circuit controlling the drive circuit. The control circuit, when switching the driver circuit from a PWM-driving state to a linear-driving state, controls the timing of the switching such that the path of the output current does not change between before and after the switching, and in addition, in the middle of the switching, switches the driver circuit to a high-output-impedance state momentarily.