Motor Control Device for Rapid Deceleration

Solution Overview

Problem

Existing motor control devices face issues with rapid deceleration control, leading to current overshoot, overcurrent, and overvoltage due to insufficient motor loss increase, which can cause damage to motors and inverters, and are difficult to accurately control due to non-linear voltage variations in the DC circuit section.

Innovation Solution

A motor control device with a deceleration controller that calculates and amplifies the command voltage amplitude based on the DC circuit section voltage and current signals to control rapid deceleration, incorporating an excitation controller and current controller to manage voltage and current amplification factors, preventing overvoltage and overcurrent through precise control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the amplitude of voltage applied to the motor is amplified during deceleration to increase motor loss, then rapid deceleration is achieved, but current overshoot and overcurrent occur

Engineering Contradiction:

Improvedeceleration speedVSAvoidcurrent overshoot and overcurrent

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent changes the voltage amplitude parameter dynamically during deceleration by multiplying the command voltage by an amplification factor greater than 1. This parameter change increases motor loss (copper loss and iron loss) to enable rapid deceleration while the control system monitors and limits the amplification to prevent excessive current

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback control by detecting the actual motor current and comparing it with the command current. When current overshoot or overcurrent is detected, the control system adjusts the voltage amplification factor or stops amplification to bring the current back within safe limits, thus preventing damage to the motor and inverter

Inventive Principle:

Principle #23Feedback

2Reliability

If the command voltage amplitude is amplified to suppress regenerated energy, then overvoltage of DC circuit section is prevented, but control complexity increases due to non-linear voltage variations

Engineering Contradiction:

Improveovervoltage protectionVSAvoidcontrol loop complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the voltage amplitude parameter dynamically during deceleration by multiplying the command voltage by an amplification factor greater than 1. This parameter change increases motor loss (copper loss and iron loss) to enable rapid deceleration while the control system monitors and limits the amplification to prevent excessive current

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback control by detecting the actual motor current and comparing it with the command current. When current overshoot or overcurrent is detected, the control system adjusts the voltage amplification factor or stops amplification to bring the current back within safe limits, thus preventing damage to the motor and inverter

Inventive Principle:

Principle #23Feedback

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 suppresses regenerated energy and stabilizes rapid deceleration by preventing overvoltage and overcurrent, allowing for smooth and stable motor deceleration while reducing the complexity of control loop adjustments.

Implementation Method 1

The inverter rectifies and converts power from a line power source to DC power and further converts the DC power to AC power having a voltage and a frequency suitable for driving the motor

Methodology Applied

Scientific EffectRectification:

Implementation Method 2

The inverter rectifies and converts power from a line power source to DC power and further converts the DC power to AC power

Methodology Applied

Scientific EffectPower conversion:

Implementation Method 3

A resistor for dissipating regenerated energy from the motor and the DC voltage smoothing capacitor are connected to the DC circuit section of the inverter

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 4

A resistor for dissipating regenerated energy from the motor and the DC voltage smoothing capacitor are connected to the DC circuit section of the inverter

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 5

the amplitude of voltage applied to the motor is amplified during deceleration to increase the current of the motor and the corresponding magnetic flux of the motor, whereby copper loss and iron loss of the motor is increased to increase the motor loss

Methodology Applied

Scientific EffectCopper loss: Joule Heating

Implementation Method 6

the amplitude of voltage applied to the motor is amplified during deceleration to increase the current of the motor and the corresponding magnetic flux of the motor, whereby copper loss and iron loss of the motor is increased to increase the motor loss

Methodology Applied

Scientific EffectIron loss:

Data Source

PatentUS9614467B2Motor control device

Publication Date: 2017.04.04 MITSUBISHI ELECTRIC CORP

AI summary

The voltage amplification factor during rapid deceleration control of a motor is set to a value obtained by adding a first voltage amplification factor calculated with reference to the voltage of the DC circuit section of the inverter using a predetermined function and a low-pass filter and a second voltage amplification factor calculated with reference to the inverter current using a PI control. And both calculations are performed in parallel.