JP2013537956A - Electric motor pump control incorporating pump element position information - Google Patents

Abstract

A method and system for controlling an electric motor of a pump to offset pressure pulsations generated by at least one pump element and reduce noise, vibration, and harshness generated by the pump. The position of at least one pump element of the pump and the position of the shaft of the electric motor are determined. The pump stroke position is determined from the position of the pump element relative to the position of the electric motor shaft. The electric power sent to the electric motor is controlled according to the pump stroke position.
[Selection] Figure 1

Description

  [0001] The present invention relates to methods and systems for improving (or reducing) noise, vibration, and harshness ("NVH") in the control of an electric motor of a hydraulic pump. More particularly, embodiments of the present invention use information about pump element position to control an electric motor that drives a pump to control the power of the motor and reduce the NVH generated by the pump. Relates to a method and system.

  [0002] Generally, systems including radial hydraulic pumps driven by electric motors are known in the industry. Examples of these hydraulic systems include the Electronic Stability Program (ESP®) by Robert Bosch, more specifically the ESP® Premium system, which is a conventional hydraulic brake system (but it is an electric machine Can perform the function of the brake system). The ESP® premium system uses a hydraulic pump with six pistons that are moved by an eccentric cam that is rotated by an electric motor. Other known hydraulic pump systems include fewer pistons (eg, two or three).

  [0003] A characteristic common to systems including hydraulic pumps driven by electric motors is that pumping produces pressure pulsations, which generate system noise and vibration. Depending on the number of pistons and the speed of the electric motor, the level of noise and vibration varies from system to system.

  [0004] There are various methods that help to reduce various types of NVH. For example, a counterbalance effect method is applied to help reduce the vibration of an engine (eg, a V-twin motorcycle engine). In order to minimize engine vibrations, a mass is used to balance an engine with an imbalance and balance the engine (engine weights or forces are offset from each other). Other methods for reducing noise are disclosed, for example, in noise canceling headphones. However, the previously disclosed methods for reducing NVH have not been proposed to reduce hydraulic pump noise and vibration by adjusting the power of the pump's electric motor based on the position of the pump elements.

  [0005] Therefore, there is a need for improved methods and systems for controlling and reducing NVH provided by hydraulic pump systems driven by electric motors. Embodiments of the present invention use information about pump element position relative to pump stroke to control and reduce NVH of an electric motor of a hydraulic pump by manipulating or controlling the power of the electric motor based on the pump stroke position. To do. Embodiments are applicable to both brush and brushless direct current (“DC”) motors.

  [0006] The present invention provides a method for controlling an electric motor of a pump to offset pressure pulsations generated by at least one pump element and reduce noise, vibration, and harshness generated by the pump. This method determines the position of at least one pump element of the pump and the position of the shaft of the electric motor. Furthermore, the pump stroke position is determined from the position of the pump element relative to the position of the shaft of the electric motor. The electric power sent to the electric motor is controlled according to the pump stroke position.

  [0007] The present invention further provides a system for controlling an electric motor of a pump to reduce noise, vibration, and harshness generated by at least one pump element of the pump. The system includes a controller and a plurality of sensors connected to the controller. Each of the sensors is configured to send information to the controller, and a network connects the sensor to the controller. The controller determines the position of the pump element and the position of the shaft of the electric motor. Further, the controller determines the pump stroke position from the position of the pump element with reference to the position of the shaft of the electric motor. Finally, the controller controls the power sent to the electric motor according to the pump stroke position.

  [0008] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

[0009] FIG. 5 is a diagram of an electric motor of a pump and components for controlling the electric motor using information regarding pump element position. [0010] FIG. 1 is a schematic diagram of a system for controlling an electric motor of a pump. [0011] FIG. 3 is a block diagram of a pump electric motor control module. [0012] FIG. 2 is a graph showing a target power profile used by the system for controlling the electric motor of the pump shown in FIG. 1, wherein the target power is in phase with the pump element position. [0013] FIG. 2 is a graph illustrating a target power profile used by the system for controlling the electric motor of the pump shown in FIG. 1, wherein the target power is out of phase with the pump element position. [0014] FIG. 2 is a graph illustrating a target power profile used by the system for controlling the electric motor of the pump shown in FIG. 1, where the frequency of the target power is twice the pump element stroke.

  [0015] Prior to describing embodiments of the present invention in detail, the present invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings in the application of the invention. It should be understood. The invention is capable of other embodiments and of being practiced or carried out in various ways.

  [0016] As will be apparent to those skilled in the art, the system shown in the figure is a model of what an actual system would look like. It should also be noted that the present invention can be implemented using multiple hardware and software based devices and multiple differently structured components. Many of the modules and logical structures described can be implemented in software running on a microprocessor or similar device, or in hardware using various components. As will be described in subsequent paragraphs, the specific configurations shown in the drawings are illustrative of embodiments of the invention and other alternative configurations are possible. Furthermore, capitalized terms are used throughout the specification. Such terms are used to follow convention and to help associate the description with coding examples, formulas, and / or drawings. However, the use of capital letters alone does not suggest or infer a specific meaning. Accordingly, the claims should not be limited to the specific examples or terms provided.

  [0017] FIG. 1 illustrates one embodiment of a system for controlling an electric motor of a pump using information regarding pump element position (eg, piston). The pump electric motor control system 12 generally includes a hydraulic pump 10 and a position sensor 20 (not shown) installed on or around the shaft 17 of the electric motor 18 of the pump 10. In addition, the pump electric motor control system 12 includes a controller 24 (FIG. 2) and a power control device 25 (FIG. 3) that manipulates the power sent to the electric motor 18. In one of the embodiments, the system 12 uses several position sensors. However, as will be described in more detail below, the system 12 can also operate with one sensor 20 or no sensor at all. Moreover, the arrangement and position of the sensors 20 in the system 12 can be varied depending on the different embodiments of the system and the type of sensors used in those embodiments. In general, the sensor 20 is directly connected to the controller 24. In one embodiment, the sensors are connected to a network, such as a controller area network (“CAN”) bus 22 that is connected to the controller 24.

  As further shown in FIG. 1, the hydraulic pump 10 includes an electric motor 18, an eccentric cam (or simple “eccentricator”) 14, a rotating shaft 17, and several pump elements (pistons) 16. Including. Pump 10 is operably connected to and driven by motor 18. In one embodiment, the system 12 includes a pump 10 with three pump pistons 16. In alternative embodiments, the system 12 can include pumps with different numbers of pump pistons (2, 4, 6, etc.). The pump element 16 is installed near the motor 18 and is pushed up and down by the eccentric 14 rotated by the shaft 17 of the motor 18. A number of position sensors 20 (not shown) are operably coupled to the shaft 17 of the motor 18 and connected to the controller 24.

  In the embodiment shown in FIGS. 1-3, the system 12 is based on the angular position of the shaft 17 (ie, based on the pump stroke) to control the power delivered to the electric motor 18. ) Determine the position of the pump element 16 (as a function of time). The rotation of the shaft 17 of the electric motor 18 has a certain relationship to the movement of the pump element 16. Thus, by controlling the power of the electric motor 18 relative to this pump stroke position, the system 12 affects (ie, reduces) the noise and vibration levels generated by the pump 10. In other words, the system 12 determines whether the pump element 16 is pumping fluid at a particular moment, where the system 12 pulses the motor power or otherwise based on the pump element position. Motor power can be controlled.

  [0020] As described in further detail below, the position of pump element 16 and shaft 17 may be monitored directly or by using one position sensor or multiple position sensors, or monitoring and measuring motor voltage. Can be determined indirectly. After the position of the pump element is determined, the system selects a “target power profile” from a table with various target power profiles stored in the controller memory to adjust the power delivered to the motor 18. This target power is based on the previously determined pump element position. The system 12 uses a power control device 25 (amplifier, transducer, or another type of conversion device) to manipulate the electrical energy delivered to the pump motor 18 and cause pressure pulsations that cause a stroke of the reciprocating pump element 16. Affect (ie offset).

  [0021] In one embodiment of the invention, the system 12 obtains information regarding the position of the pump element directly by using several position sensors. These position sensors 20 are arranged on or around the shaft 17 of the electric motor 18. Controller 24 receives appropriate sensor signals and inputs from position sensor 20 that indicate the position of pump element 16 and the angular position of shaft 17. For example, direct position measurement can be achieved by using a Hall effect sensor or a rotary encoder. Other position sensors can also be used.

  [0022] One embodiment of the present invention utilizes a sophisticated (and more expensive) sensor array having a number of position sensors (Hall effect sensors) positioned on or about the rotational axis 17. By using an advanced sensor array, the system 12 obtains more accurate position information for the pump elements and shafts.

  [0023] In an alternative embodiment where the system 12 is constructed at a low cost, only a single position sensor is used to determine the pump stroke position. In that case, the system receives position information for only a portion of the rotation of the shaft 17 (eg, the system can receive a 5 degree pulse per rotation). Next, the system 12 determines the rest of the rotation based on various additional factors: the rpm of the electric motor, the total torque acting on the motor, and the overall pressure that the pump 10 is acting against. The position of the shaft 17 is estimated. The system combines these factors with initial sensor measurements to infer the future position of the pump element and then verifies that this position is correct.

  [0024] In another alternative embodiment, the system 12 uses electrical monitoring to indirectly determine the position of the pump element 16 relative to the pump stroke. In this alternative embodiment, system 12 determines the position of pump element 16 and shaft 17 without any position sensor 20. For example, in a brush DC motor, the system 12 measures the electrical signal of the motor wire as the communicator switches from one winding to another to determine the position of the shaft 17 and pump element 16. A similar method for indirectly determining the position of the electric motor and pump elements is described in EP2096749A1. The system 12 can also indirectly determine the position of the electric motor and pump elements in the brushless DC motor. Thus, the position of the pump element 16 and the shaft 17 can still be determined indirectly without using a position sensor. Although it is possible to do so, the electric motor frequently starts and stops, which makes it difficult to keep track of the position of the motor element, so the pump element position is indirectly or "sensorless" It is not preferable for the electronic stability control system to determine the above.

  [0025] FIG. 2 schematically illustrates the function of the pump electric motor control system 12 of FIG. 1 in more detail. As shown in FIG. 2, the control system 12 includes a controller 24 and one or more sensors 20. Controller 24 obtains sensor readings directly from one or more of sensors 20. In some situations, particularly when the system uses fewer sensors to determine the position of the pump element 16, corrected sensor readings are used in the controller 24 rather than raw data. For example, in some situations, the controller 24 corrects one or more of the sensor readings by providing an offset. The offset is used to compensate for sensor aging, contamination, and other signal corruption that may occur.

  [0026] In many implementations, the controller 24 includes a processor, such as a microcontroller or microprocessor, associated electronic circuitry, such as input / output circuits, various programmed modules, and one or more memory components. Including.

  [0027] As shown in FIG. 2, the controller 24 includes an input / output interface 40, an electronic processing unit ("EPU") 42, a random access memory ("RAM") 44 and a read only memory ("ROM"). One or more memory modules, such as 45. The input / output interface 40 sends and / or receives information including sensor readings from the sensor 20. The controller 24 further includes a pump electric motor control (“PEMC”) module 50 that is executed by the EPU 42. The PEMC module 50 is designed to determine the position of the shaft 17 and the pump element 16 with respect to the pump stroke, and controls the power of the electric motor 18 with respect to the determined control position.

  [0028] The EPU 42 receives information (such as sensor readings) from the input / output interface 40 and processes the information by executing one or more applications or modules. The application or module is stored in a memory such as the ROM 45. The EPU 42 stores information (eg, information received from the sensor 20 or information generated by an application or module executed by the EPU 42) in the RAM 44. For example, the RAM 44 can store various positions of the shaft 17 and pump element 16 detected by the sensor 20. Moreover, the RAM 44 can further receive and store data from the PEMC module 50 or other components of the system 12. The RAM 44 further stores a table with various target power profiles accessed by the PEMC module 50 to select a target control power for operating the electric motor 18. In the embodiment shown in FIG. 2, a RAM is used. In other embodiments, other memory devices may be implemented.

  [0029] FIG. 3 illustrates the operation of the pump electric motor control ("PEMC") module 50 in more detail. In the particular embodiment shown, the PEMC module 50 determines the position (stroke) of the pump element 16 having a defined relationship with the electric motor 18 as the motor shaft 17 rotates, and the electric motor relative to the pump stroke position. 18 power is configured to be controlled. The PEMC module 50 receives sensor signals from the sensor 20 (or a single sensor in an alternative embodiment) through the input / output interface 40 and determines the position of the pump element 16 based on these signals. The PEMC module 50 determines the pump stroke position, i.e., the position of the pump element 16 relative to the pump stroke (i.e., movement of the pump element as the pump is moving, or whether the pump element is pumping fluid). ). The pump stroke position is determined based on the position of the electric motor 18 (using the motor shaft position) relative to the position of the pump element 16. Next, the PEMC module 50 selects a target control power from a table having a target power profile according to the determined pump stroke position.

  [0030] The PEMC module 50 uses the power control device 25 to manipulate the power sent to the electric motor 18 in accordance with the selected target control power. Controlling the power delivered to the motor 18 includes voltage control (eg, pulse width modulation control) or current control (eg, by specific hardware), depending on the implementation of the system. By adjusting the power of the electric motor 18 relative to the stroke of the pump element 16, the PEMC module 50 helps to affect (ie, reduce) the noise, vibration, and harshness generated by the pump 10. In one embodiment, power control device 25 is a metal oxide semiconductor field effect transistor (MOSFET) control device. In alternative embodiments, power control device 25 may be an amplifier, transducer, or other control device.

  [0031] In order to change the power of the motor 18 in a timely manner based on the position of the pump element 16, the system 12 runs the PEMC module 50 at high speed to follow the repetitive pressure pulses generated by the pump element 16. For example, in a pump with two pump elements, the motor 18 operates at 5000 rpm (equal to 83.3 Hz), resulting in 167 pulses / second (5000 rpm × 2). System 12 performs PEMC module 50 approximately 10 times faster than individual pump element cycles. Therefore, in this case, the PEMC module 50 is executed every (1 second / 167 pulses) × (0.1) = 0.6 milliseconds. During the execution time of the PEMC module (0.6 milliseconds = 0.006 seconds), the system 12 determines the pump stroke position, selects the target control power from a table with the target power profile, and the voltage of the motor 18 Adjust.

  [0032] The operation of the pump electric motor control ("PEMC") module 50 is further illustrated in FIGS. In particular, FIGS. 4-6 show several target power profiles that are stored in RAM 44 and used by PEMC module 50 to select target control power and control electric motor 18. In various embodiments of the present invention, additional target power profiles can be generated and used. The waveform graphs of FIGS. 4-6 illustrate an embodiment of the present invention in which the pump 10 includes three pump elements, i.e., a piston 16 (as shown in FIG. 1). In alternative embodiments of the invention, a different number of pump elements can be used. The waveforms in the lower part of FIGS. 4 to 6 represent the movement / stroke of the pump element 16. In general, these pump elements 16 generate a pressure pulse every 120 degrees. The measured value on the left side of the graph indicates the position of the pump element with reference to the pump stroke (in mm). The measured value on the right side of the graph indicates the target control power level (in amperes). The measured value at the bottom of the graph indicates the angular position (in degrees) of the shaft 17. The target control power shown in the upper part of the graph is a function of shaft position relative to pump element position. For example, if the pump element is at a 240 degree position, the target power is 8.5 amps.

  FIG. 4 shows one target power profile used by the system 12. After system 12 determines the pump stroke position based on the pump element position and shaft angular position, system 12 selects a target power profile from a table stored in RAM 44. FIG. 4 shows a situation where the target power is in phase with the pump element position. In other words, the target power will increase when the pump is moving and decrease when the pump is not moving. Thus, the system 12 supplies maximum power to the electric motor 18 when the pump is doing most of the work.

  [0034] FIG. 5 shows a second target power profile used by the system 12. In FIG. 5, the target power is out of phase with the pump element position. In other words, the target power will be low when the pump element is moving, and the target power will increase when the pump is not moving. Thus, the target power generates a vibration wave that is exactly out of phase with the pump noise wave, and the two waves will interact. Under appropriate conditions, these two antiphase oscillations can be combined, resulting in a smaller wave.

  [0035] FIG. 6 shows a third target power profile used by the system 12. The target power profile shown in FIG. 6 is that when the system 12 determines the pump element position, the system 12 adjusts the target power (at an increased or decreased level) to obtain the best overall performance of the pump 10. It shows that you can. In this case, the target power is twice the pump element stroke and is in phase with the pump element position. The system manipulates the target power with respect to the pump stroke in such a manner to improve the NVH of the pump.

  [0036] Various features and advantages of the invention are set forth in the following claims.

Claims (20)

A method of controlling an electric motor of a pump to cancel pressure pulsations generated by at least one pump element and reduce noise, vibration and harshness generated by the pump,
Determining the position of at least one pump element of the pump;
Determining the position of the shaft of the electric motor;
Determining a pump stroke position from the position of the at least one pump element relative to the position of the shaft of the electric motor;
Controlling power delivered to the electric motor in response to the pump stroke position.   The method of claim 1, further comprising controlling the power delivered to the electric motor by using a target control power.   The method of claim 1, further comprising directly determining the position of the pump element and the position of the shaft of the electric motor.   The method of claim 1, further comprising indirectly determining the position of the pump element and the position of the shaft of the electric motor.   4. The method of claim 3, further comprising directly determining the position of the pump element and the position of the shaft of the electric motor by using a position sensor.   The method of claim 1, further comprising selecting a target power profile from a table having various target power profiles stored in a memory of the controller.   The method of claim 6, further comprising selecting the target control power from the target power profile, wherein the target control power is a function of the position of the shaft and the position of the pump element.   The method of claim 1, further comprising determining the pump stroke position by executing a pump electric motor control (“PEMC”) module.   The method of claim 8, further comprising executing the pump electric motor control (“PEMC”) module at a faster rate than individual pump element cycles.   The method of claim 7, further comprising selecting a target control power that is in phase with the position of the pump element.   The method of claim 1, wherein controlling the power delivered to the electric motor comprises voltage control or current control. A system for controlling an electric motor of the pump to reduce noise, vibration, and harshness generated by at least one pump element of the pump, the system comprising:
A controller,
A plurality of sensors connected to the controller, each of the sensors configured to send information to the controller;
A network connecting the sensor to the controller,
The controller (1) determines the position of the pump element and the position of the shaft of the electric motor, and (2) determines the pump stroke position from the position of the pump element relative to the position of the shaft of the electric motor. And (3) a system programmed to control power delivered to the electric motor in response to the pump stroke position.   The system of claim 12, wherein the controller further comprises a pump electric motor control (“PEMC”) module that receives a sensor signal from the sensor and determines the pump stroke position.   The system of claim 12, wherein the controller is programmed to select a target power profile from a table having various target power profiles stored in a memory of the controller.   The controller is programmed to select a target control power from the target power profile, the target control power being determined based on the position of the shaft relative to the position of the pump element. The system described in.   The system of claim 15, wherein the controller is programmed to select a target control power that is in phase with the position of the pump element.   The system of claim 15, wherein the controller is programmed to select a target control power that is out of phase with the position of the pump element.   The system of claim 15, wherein the controller is programmed to select a target control power that operates at any increased or decreased level to improve the overall performance of the pump.   The system of claim 12, wherein the controller is further programmed to control the power delivered to the electric motor by using a power control device.   The system of claim 12, wherein the controller is further programmed to control the power delivered to the electric motor by voltage control or current control.

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