# US 9,708,794 B2 · Electromechanical drive for a working machine

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- Number: US 9,708,794 B2
- Document ID: US9708794B2
- Status: Granted
- Kind: B2
- Application number: 14/615,481
- Filed: 2015-02-06
- Published: 2016-08-25
- Granted: 2017-07-18
- Earliest claimed: 2014-02-07
- Assignees: Visedo Oy
- Applicants: Visedo Oy
- Inventors: Kimmo Rauma; Ville Naumanen
- Web page: https://patentgrep.com/patent/US9708794B2

## CPC

- E02F 9/2075: {of the hybrid type (for vehicles in general B60W20/00)}
- B60K 6/26: characterised by the motors or the generators
- B60K 6/46: Series type
- B60K 6/54: Transmission for changing ratio
- B60K 7/0007: {the motor being electric}
- B60K 17/043: {Transmission unit disposed in on near the vehicle wheel, or between the differential gear unit and the wheel}
- B60W 10/08: including control of electric propulsion units, e.g. motors or generators
- B60W 10/10: including control of change-speed gearings
- B60W 20/30: Control strategies involving selection of transmission gear ratio {(control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H)}
- E02F 9/202: {Mechanical transmission, e.g. clutches, gears (clutches per se F16D, gears per se F16H)}
- E02F 9/2079: {Control of mechanical transmission (for hydrostatic transmission or hydraulic torque converter E02F9/2253)}
- B60K 2007/0061: {the motor axle being parallel to the wheel axle}
- B60W 2300/17: Construction vehicles, e.g. graders, excavators
- B60W 2710/086: Power
- B60W 2710/1005: Transmission ratio engaged
- B60W 2710/105: Output torque
- B60Y 2200/92: Hybrid vehicles
- B60Y 2400/61: Arrangements of controllers for electric machines, e.g. inverters
- E02F 3/34: with bucket-arms {, i.e. a pair of arms, e.g. manufacturing processes, form, geometry, material of bucket-arms (with a single arm E02F3/283)} directly pivoted on the frames of tractors or self-propelled machines
- Y02T 10/40: Engine management systems
- Y02T 10/62: Hybrid vehicles
- Y10S 903/906: Motor or generator
- Y10S 903/917: with transmission for changing gear ratio
- Y10S 903/93: Conjoint control of different elements
- E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00)
- B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60Y: INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

An electromechanical drive comprises an electrical machine (101a), an electrical power converter (103) for converting voltage of an external electrical system to voltage suitable for the electrical machine, and a gearbox (111a) for mechanically connecting the electrical machine to an actuator (112a) and capable of providing selectable transmission ratios between the electrical machine and the actuator. The electrical power converter comprises a controller for selecting one of the selectable transmission ratios at least partly on the basis of a) first data related to actual and/or desired torque-speed operating point of the actuator and b) second data related to functional properties of at least the electrical machine. Thus, the transmission ratio can be selected at least partly from the viewpoint of the electrical machine taking into account for example the most advantageous speed range and/or torque range of the electrical machine.

## Claims

### Claim 1

An electromechanical drive, comprising:
an electrical machine;
a gearbox having a first shaft connected to the electrical machine and a second shaft for driving an actuator, the gearbox being capable of providing selectable transmission ratios each being a ratio of a rotational speed of the first shaft to a rotational speed of the second shaft; and
an electrical power converter for converting voltage of an external electrical system into voltage suitable for the electrical machine,
wherein the electrical power converter comprises:
a controller for selecting one of the selectable transmission ratios on the basis of a) first data related to a torque-speed operating point of the second shaft when driving the actuator and b) second data related to functional properties of at least the electrical machine, and
a signal output for delivering, to the gearbox, a control signal so as to set the gearbox to operate at the selected one of the selectable transmission ratios.

### Claim 2 (depends on 1)

The electromechanical drive according to claim 1, wherein the controller is adapted to control the gearbox to shift from a higher one of the selectable transmission ratios to a lower one of the selectable transmission ratios in response to a situation in which a rotational speed of the electrical machine achieves a field weakening point where voltage of the electrical machine achieves a maximum voltage available from electrical power converter.

### Claim 3 (depends on 1)

The electromechanical drive according to claim 1, wherein the controller is adapted to select such one of the selectable transmission ratios which, according to the second data, yields such a torque-speed operating point of the electrical machine where losses comprising at least losses of the electrical machine are smaller than when using another one of the selectable transmission ratios.

### Claim 4 (depends on 3)

The electromechanical drive according to claim 3, wherein the controller is adapted maintain a lookup-table for identifying the one of the selectable transmission ratios on the basis of the first data, and wherein the first data is indicative of estimates of at least two of the following: power transferred by the second shaft, rotational speed of the second shaft, torque acting on the second shaft.

### Claim 5 (depends on 1)

The electromechanical drive according to claim 1, wherein the controller is adapted to select one of the selectable transmission ratios so that a target value of torque Tref/Q of the electrical machine is as near as possible to torque Topt corresponding to such a torque-speed operating point of the electrical machine where power of the electrical machine is P and losses comprising at least losses of the electrical machine are smaller than when producing the power P with torque different from Topt, Tref being a target value of torque acting on the second shaft, Q being the selected one of the selectable transmission ratios, and P being Tref×rotational speed of the second shaft.

### Claim 6 (depends on 5)

The electromechanical drive according to claim 5, wherein the controller is adapted to produce a value of the torque Topt at least partly on the basis of the second data and the first data, where the first data is indicative of the target value Tref of the torque acting on the second shaft and an estimate of the rotational speed of the second shaft.

### Claim 7 (depends on 6)

The electromechanical drive according to claim 6, wherein the controller is adapted maintain a lookup-table for providing the value of the torque Topt on the basis of the target value Tref of the torque acting on the second shaft and the estimate of the rotational speed of the second shaft.

### Claim 8 (depends on 1)

The electromechanical drive according to claim 1, wherein the controller is adapted to select one of the selectable transmission ratios so that a target value of rotational speed Sref×Q of the electrical machine is as near as possible to rotational speed Sopt corresponding to such a torque-speed operating point of the electrical machine where power of the electrical machine is P and losses comprising at least losses of the electrical machine are smaller than when producing the power P at rotational speed different from Sopt, Sref being a target value of rotational speed of the second shaft, Q being the selected one of the selectable transmission ratios, and P being Sref×torque acting on the second shaft.

### Claim 9 (depends on 8)

The electromechanical drive according to claim 8, wherein the controller is adapted to produce a value of the rotational speed Sopt at least partly on the basis of the second data and the first data, where the first data is indicative of the target value Sref of the rotational speed of the second shaft and an estimate of the torque acting on the second shaft.

### Claim 10 (depends on 9)

The electromechanical drive according to claim 9, wherein the controller is adapted maintain a lookup-table for providing the value of the rotational speed Sopt on the basis of the target value Sref of the rotational speed of the second shaft and the estimate of the torque acting on the second shaft.

### Claim 11

A mobile working machine, comprising:
a combustion engine; and
an electromechanical power transmission chain between the combustion engine and one or more actuators of the mobile working machine,
wherein the electromechanical transmission chain comprises at least one electromechanical drive comprising:
an electrical machine,
a gearbox having a first shaft connected to the electrical machine and a second shaft for driving one of the actuators, the gearbox being capable of providing selectable transmission ratios each being a ratio of a rotational speed of the first shaft to a rotational speed of the second shaft, and
an electrical power converter for converting input voltage of the electrical power converter into voltage suitable for the electrical machine,
and wherein the electrical power converter comprises:
a controller for selecting one of the selectable transmission ratios on the basis of a) first data related to a torque-speed operating point of the second shaft when driving the actuator and b) second data related to functional properties of at least the electrical machine, and
a signal output for delivering, to the gearbox, a control signal so as to set the gearbox to operate at the selected one of the selectable transmission ratios.

### Claim 12

A method for controlling an electromechanical drive that includes an electrical machine, an electrical power converter for converting voltage of an external electrical system to voltage suitable for the electrical machine, and a gearbox having a first shaft connected to the electrical machine and a second shaft for driving an actuator, the gearbox being capable of providing selectable transmission ratios each being a ratio of a rotational speed of the first shaft to a rotational speed of the second shaft, the method comprising:
selecting, by the electrical power converter, one of the selectable transmission ratios on the basis of a) first data related to a torque-speed operating point of the second shaft when driving the actuator and b) second data related to functional properties of at least the electrical machine; and
delivering, from the electrical power converter to the gearbox, a control signal so as to set the gearbox to operate at the selected one of the selectable transmission ratios.

### Claim 13

A non-volatile computer readable medium encoded with a computer program for controlling an electromechanical drive that includes an electrical machine, an electrical power converter for converting voltage of an external electrical system to voltage suitable for the electrical machine, and a gearbox having a first shaft connected to the electrical machine and a second shaft for driving an actuator, the gearbox being capable of providing selectable transmission ratios each being a ratio of a rotational speed of the first shaft to a rotational speed of the second shaft, the computer program comprising computer executable instructions for controlling a programmable processing system of the electrical power converter to:
select one of the selectable transmission ratios on the basis of a) first data related to a torque-speed operating point of the second shaft when driving the actuator and b) second data related to functional properties of at least the electrical machine; and
transmit, from the electrical power converter to the gearbox, a control signal so as to set the gearbox to operate at the selected one of the selectable transmission ratios.