Mining vehicle and method for starting an AC electric motor of a mining vehicle

Patent metadata

Field	Value
Publication number	US-11063536-B2
Application number	US-201916601122-A
Country	US
Kind code	B2
Filing date	Oct 14, 2019
Priority date	Oct 15, 2018
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

For starting an AC electric motor of a mining vehicle, it is first accelerated to a first speed with a second AC voltage provided by an onboard battery-powered inverter of the mining vehicle. A phase of a first AC voltage taken from an external grid is compared to a phase of said second AC voltage. If the phase difference between the first and second AC voltages is larger than a predetermined limit, the speed at which said inverter rotates said AC electric motor is changed. If the difference between the phases of the first and second AC voltages is smaller than the predetermined limit, a change is made from rotating the AC electric motor with the second AC voltage to rotating the AC electric motor with the first AC voltage.

First claim

The invention claimed is:

1. A mining vehicle, comprising:
an AC electric motor arranged for powering at least one of moving and drilling functions of the mining vehicle;
an external grid connector arranged for receiving a first AC voltage from an external grid;
a battery, and an inverter coupled between said battery and said AC electric motor, the inverter being arranged for providing a second AC voltage;
a first controllable switch between said external grid connector and said AC electric motor;
a second controllable switch between said inverter and said AC electric motor;
a control computer coupled to said first controllable switch and to said second controllable switch, and configured to control the coupling of said first and second AC voltages to said AC electric motor;
a first detector configured to detect a phase of said first AC voltage;
a second detector configured to detect a phase of said second AC voltage; and
a synchronization comparator coupled to said first and second detectors and configured to produce a synchronization signal indicative of a phase difference between said first and second AC voltages, wherein said control computer is configured to implement a motor start-up sequence that includes closing said second switch for coupling said second AC voltage to said AC electric motor, monitoring said synchronization signal to notice said phase difference between said first and second AC voltages becoming smaller than a predetermined limit, opening said second switch, and closing said first switch for coupling said first AC voltage to said AC electric motor, wherein the control computer is coupled to a first control input of the inverter and configured to provide the inverter with a speed reference signal, a speed detector of the AC electric motor is coupled to a second control input of the inverter and configured to provide the inverter with a speed feedback signal, the inverter being configured to control the provision of said second AC voltage to make said speed feedback signal match said speed reference signal.

2. The mining vehicle according to claim 1 , wherein the inverter is coupled to an input of the control computer and configured to provide the control computer with a motor speed indicator signal.

3. The mining vehicle according to claim 1 , further comprising a user interface coupled to said control computer arranged for allowing information to be exchanged between the control computer and a user.

4. The mining vehicle according to claim 1 , wherein the control computer is configured to proceed from said monitoring of said synchronization signal to said opening of said second switch as a response to noticing that the phase difference between said first and second AC voltages has remained smaller than said predetermined limit for a time that is longer than a predetermined delay.

5. The mining vehicle according to claim 1 , wherein said mining vehicle is a rock-drilling rig.

6. A method for starting an AC electric motor of a mining vehicle, comprising the steps of:
accelerating said AC electric motor to a first speed with a second AC voltage provided by an onboard battery-powered inverter of said mining vehicle; and
comparing a phase of a first AC voltage taken from an external grid to a phase of said second AC voltage;
in response to a difference between said phases of said first and second AC voltages being larger than a predetermined limit, changing the speed at which said inverter rotates said AC electric motor; and
in response to said difference between said phases of said first and second AC voltages being smaller than said predetermined limit, changing from rotating said AC electric motor with said second AC voltage to rotating said AC electric motor with said first AC voltage.

7. The method according to claim 6 , further comprising the steps of using said battery-powered inverter to generate said second AC voltage at a controllable frequency, receiving in said battery-powered inverter a speed reference signal indicative of a desired rotation speed of said AC electric motor and a speed feedback signal indicative of a detected rotation speed of said AC electric motor, and
controlling said frequency of said second AC voltage to make said speed feedback signal match said speed reference signal.

8. The method according to claim 6 , wherein said changing from rotating said AC electric motor with said second AC voltage to rotating said AC electric motor with said first AC voltage is done in response to noticing that the phase difference between said first and second AC voltages has remained smaller than said predetermined limit for a time that is longer than a predetermined delay.

Assignees

• Sandvik Mining & Construction Oy

Inventors

• Tiihonen Tommi
• Vatanen Harri
• Ristimäki Ville

Classifications

• E21B7/025

  Rock drills, i.e. jumbo drills · CPC title

• B60L15/007

  Physical arrangements or structures of drive train converters specially adapted for the propulsion motors of electric vehicles · CPC title

• B60L53/20

  characterised by converters located in the vehicle · CPC title

• B60L2200/40

  Working vehicles · CPC title

• B60L1/003 Primary

  to auxiliary motors, e.g. for pumps, compressors · CPC title