Motor Controller Pin Sharing and Torque Smoothing

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Solution Overview

Problem

Existing motor control systems face challenges in efficiently switching between open-loop and closed-loop control methods without sensors, leading to torque oscillations and noise during method transitions, and require multiple input pins for setting current command values and limits.

Innovation Solution

A motor controller that includes a first current command value generator, an analog-to-digital converter for generating a second current command value, and a current limit generator to produce an upper limit value, allowing for seamless switching between open-loop and closed-loop control methods based on these values, reducing torque oscillations and noise, and minimizing the number of input pins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple input pins are used to set current command values and limits separately, then the motor controller can precisely control current parameters, but the device size and complexity increase

Engineering Contradiction:

Improvecurrent parameter control precisionVSAvoidnumber of input pins

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple input pins into a single shared input pin that accepts both current command value and current limit settings. The external device sets different parameters by applying different voltage levels or signal patterns to the same pin, eliminating the need for separate pins and reducing overall device complexity while maintaining precise control capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The shared input pin is designed to serve multiple functions: it can accept current command values, current limits, and potentially other control parameters. This multi-functional design allows the motor controller to maintain precise parameter control while minimizing the number of physical pins required on the device

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If open-loop and closed-loop control methods are switched, then the motor control flexibility is improved, but torque oscillations and noise occur during transitions

Engineering Contradiction:

Improvecontrol method flexibilityVSAvoidtorque oscillations and noise

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary smoothing action by generating a smoothed current command value that transitions gradually between open-loop and closed-loop control modes. This pre-processing of the current command signal prevents abrupt changes that would cause torque oscillations and noise, allowing flexible control method switching while maintaining smooth motor operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a smoothed current command value as an intermediary element between the open-loop and closed-loop control methods. This intermediate signal acts as a buffer that reconciles the differences between the two control approaches, enabling seamless transitions without generating harmful torque oscillations or noise

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10199967B2Motor controller, motor driving apparatus, motor driving system, image forming apparatus, and conveying device

Publication Date: 2019.02.05 RICOH CO LTD

AI summary

A motor controller that controls a motor in a first control method based on a first current command value and a second control method based on a second current command value. The motor controller includes an analog-to-digital converter to generate the second current command value based on a reference signal externally input to the motor controller and a current limit generator to generate an upper limit value of the first current command value based on the second current command value.