Motor Driving Circuit Dynamic Current Limiting
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Solution Overview
Problem
Existing motor products face challenges in stabilizing motor current during start-up and transient states, leading to slow start-up speeds and peak currents, which complicates production processes.
Innovation Solution
A motor driving circuit and method that includes an inverter circuit, control circuit, current-limiting circuit, start circuit, and transient circuit, which adjust current limit values based on start, transient, and steady states to stabilize motor current, eliminating the need to adjust soft-start rates or duty cycle change rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the change rate of soft start or duty cycle is adjusted to meet peak values and smoothness requirements, then the power supply current smoothness is improved, but the start-up speed of the motor slows down and the transient state time is prolonged
Solution Approach 1:
The patent implements dynamic current limit adjustment by detecting motor operating states (standstill, acceleration, deceleration, reversal) and automatically switching between different current limit values. The controller adjusts the current limit based on real-time motor state, enabling fast start-up when needed while maintaining current smoothness during critical transitions, thus resolving the contradiction between start-up speed and current stability.
Solution Approach 2:
The patent changes the current limit parameter dynamically based on motor operating conditions. By detecting whether the motor is in standstill, acceleration, deceleration, or reversal state, the system selects appropriate current limit values from predefined sets, allowing optimal current control for each operational phase and eliminating the need for conservative soft-start adjustments.
2Object-generated harmful factors
If the change rate of soft start or duty cycle is adjusted to meet peak values and smoothness requirements, then the power supply current peak control is improved, but the transient state time is prolonged
Solution Approach 1:
The system dynamically adjusts current limits based on real-time motor state detection. During acceleration and deceleration phases, appropriate current limits are applied to control peaks without excessive soft-start restrictions. This enables the motor to exit transient states quickly while maintaining power supply current within acceptable peak values, resolving the time-loss contradiction.
Solution Approach 2:
The patent employs feedback mechanisms by continuously detecting motor operating states (through current direction and magnitude detection) and adjusting current limits accordingly. This closed-loop control ensures that current peaks are suppressed during critical transitions while minimizing the duration of transient states, as the system responds actively to motor conditions rather than using fixed conservative parameters.
3Device complexity
If existing motor products use fixed current limits, then the device complexity is reduced, but the ability to stabilize motor current during start and transient states is insufficient
Solution Approach 1:
The patent segments the motor operating conditions into distinct states (standstill, acceleration, deceleration, reversal) and applies different current limit values for each segment. This segmentation approach maintains relatively simple control logic while significantly improving current stability, as each operational phase receives optimized current control rather than a single fixed limit.
Solution Approach 2:
The controller integrates multiple functions into a single device: it detects motor state, determines appropriate current limits, and controls the inverter circuit. This multi-functional design achieves reliable current stabilization without requiring separate complex control systems for each function, balancing device complexity with performance requirements.
Data Source
AI summary
A motor driving circuit and a motor driving method are provided. The motor driving circuit is used to drive the motor and includes an inverter circuit, a control circuit, a current-limiting circuit, a start circuit and a transient circuit. The control circuit controls the inverter circuit to drive the motor with a motor control current according to a set current limit value indicated by a current-limiting signal, and outputs a steady state ready signal in response to the motor reaching a steady state. The current-limiting circuit generates the current-limiting signal according to a start state signal, or generates the current-limiting signal according to a transient signal. The start circuit outputs the start state signal when the motor starts. The transient circuit detects whether the motor is in a transient state, and outputs the transient signal in response to the motor being in a transient state.