Brushless Motor Driving Circuit Peak Hold Feedback
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Solution Overview
Problem
Conventional brushless motor driving circuits experience rotation fluctuations due to motor current variations, which affect the control of three-phase brushless motors, particularly when the motor current is large, leading to inefficiencies in speed control and torque management.
Innovation Solution
The proposed brushless motor driving system incorporates a peak hold circuit, differential voltage detecting circuit, integrating amplifier circuit, and output waveform generating circuit to calculate and adjust speed control signals based on motor current and rotational speed, ensuring stable operation by generating driving signals that minimize rotation fluctuations without reducing maximum torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional brushless motor driving circuit controls rotation at energization, then speed control is achieved, but rotation fluctuation occurs
Solution Approach 1:
The invention introduces feedback mechanisms including a detecting resistor to detect motor current, a peak hold circuit to hold the peak of detected voltage, and a computing circuit that computes the difference between held peak voltage and filtered voltage. This feedback loop continuously monitors and adjusts driving signals based on actual motor current, thereby reducing rotation fluctuation while maintaining speed control.
Solution Approach 2:
The invention replaces conventional mechanical control methods with electronic signal processing. Instead of direct mechanical control of motor energization, the system uses electronic circuits (peak hold circuit, filter circuit, computing circuit) to process voltage signals and generate corrected driving signals, thereby achieving smoother rotation control without mechanical components.
2Power
If motor current is increased for higher torque, then power output improves, but rotation fluctuation increases
Solution Approach 1:
The detecting resistor monitors motor current in real-time, and the peak hold circuit captures the peak voltage corresponding to maximum current. The computing circuit then processes this information to generate corrected driving signals that prevent excessive current surges, allowing high torque output while minimizing rotation fluctuation even at high motor currents.
Solution Approach 2:
The invention dynamically adjusts driving signal parameters based on detected motor current characteristics. By changing the timing and magnitude of driving signals according to actual current conditions (processed through peak hold and filter circuits), the system optimizes torque output while maintaining rotation stability across varying load conditions.
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 effectively reduces rotation fluctuations of the three-phase brushless motor across varying motor currents, maintaining efficient speed control and torque management without the need for additional circuits, thus enhancing the stability and performance of the motor driving system.
Implementation Method 1
a detecting resistor to which a motor current flowing through the brushless motor flows via the power device
Implementation Method 2
a peak hold circuit that outputs a second voltage obtained by holding a peak of a first voltage that is based on a detected voltage responsive to a voltage drop in the detecting resistor
Implementation Method 3
a filter circuit that outputs a third voltage, which is a direct-current component of the second voltage
Implementation Method 4
a differential voltage detecting circuit that outputs a first differential voltage between the second voltage and the third voltage
Implementation Method 5
an integrating amplifier circuit that converts a speed instruction pulse signal that is a pulse wave responsive to a rotational speed of the brushless motor into an analog voltage
Implementation Method 6
a computing circuit that calculates a second differential voltage between the analog voltage and a fourth voltage responsive to the first differential voltage, and outputs a speed control signal responsive to the second differential voltage
Data Source
AI summary
The brushless motor driving circuit includes a peak hold circuit that outputs a second voltage obtained by holding a peak of a first voltage that is based on a detected voltage responsive to a voltage drop in the detecting resistor. The brushless motor driving circuit includes a filter circuit that outputs a third voltage, which is a direct-current component of the second voltage. The brushless motor driving circuit includes a differential voltage detecting circuit that outputs a first differential voltage between the second voltage and the third voltage. The brushless motor driving circuit includes a computing circuit that calculates a second differential voltage between the analog voltage and a fourth voltage responsive to the first differential voltage, and outputs a speed control signal responsive to the second differential voltage.