ACTIVE ADAPTIVE HYDRAULIC RIPPLE CANCELLATION ALGORITHM AND SYSTEM
Hydraulic pumps/motors are used to convert between rotational motion/power and fluid motion/power. Pressure differential is achieved across the pump/motor by applying torque to either aid or impede rotation which generally results in either a pressure rise or pressure drop respectively across the unit. This torque is often supplied by an electric motor/generator. Especially in positive displacement pumps/motors this pressure differential is not a smooth value but rather it contains high frequency fluctuations known as pressure ripple that are largely undesirable. With thorough analysis it can be discovered that these fluctuations occur in a predictable manner with respect to the position (angular or linear) of the pump/motor. Using a model that contains this information, a feed-forward method of high-frequency motor torque control is implemented directly on the hydraulic pump/motor by adding to the nominal torque, a model-based torque signal that is linked to rotor position. This high-frequency signal acts directly on the hydraulic pump/motor to reduce or cancel the pressure/flow ripple of the pump/motor itself without the need for any secondary flow generating devices.
1 . A method of hydraulic ripple cancellation, comprising:
sensing an angular position of a rotor of an electric motor;
operatively coupling the electric motor to a hydraulic pump; and
operating the electric motor to impart at least one of a command torque and a command velocity on the hydraulic pump and to impart at least one of a ripple torque and a ripple velocity on the hydraulic pump based at least in part on the sensed angular position of the rotor.
2 . The method of claim 1 , wherein the hydraulic ripple is at least one of pressure ripple and fluid flow ripple.
3 . The method of claim 1 , wherein the at least one of ripple torque and ripple velocity is a variable at least one of torque and velocity that is imparted based on at least one of current electric motor torque and speed.
4 . The method of claim 1 , wherein the at least one of ripple torque and ripple velocity substantially comprises a periodic waveform.
5 . The method of claim 4 , wherein the periodic waveform comprises one or more sine waves.
6 . The method of claim 4 , wherein the periodic waveform comprises a plurality of waveforms, each having a period, magnitude, and shape.
7 . The method of claim 4 , wherein the periodic waveform at least partially cancels one or more harmonics of the hydraulic ripple.
8 . The method of claim 1 , wherein the electric motor velocity is electrically varied based at least in part on the sensed angular position of the rotor.
9 . The method of claim 1 , wherein the hydraulic pump at a constant speed is characterized by a varying flow rate with respect to angular position, and wherein at least one of torque and velocity of the electric motor is electrically controlled to compensate for this non-constant flow property.
10 . The method of claim 1 , wherein sensing of angular rotor position is accomplished by one of a rotary encoder, hall effect sensor, and sensorless control using phase voltages and currents of the electric motor.
11 . The method of claim 1 , wherein the at least one of ripple torque and ripple velocity is imparted based on a model of at least one of torque and velocity control that includes rotor position.
12 . The method of claim 11 , wherein the model of at least one of torque and velocity is feed-forward.
13 . The method of claim 11 , wherein the model of at least one of torque and velocity adapts parameters based on one or more feedback sensors.
14 . The method of claim 13 , wherein the feedback sensor is one of an accelerometer and a pressure sensor.
15 . The method of claim 11 , wherein the model of at least one of torque and velocity control comprises one of a function and a multidimensional array.
16 . The method of claim 11 , wherein independent variables in the model comprise of at least one of rotor velocity, motor torque, and hydraulic pressure.
17 . The method of claim 11 , wherein the model of at least one of torque and velocity control outputs one or more magnitude and phase values that specify the ripple cancellation waveform.
18 . The method of claim 11 , wherein the model of at least one of torque and velocity control comprises a multidimensional array that represents at least one of ripple torque and ripple velocity parameters for a plurality of rotor speeds.
19 . The method of claim 1 , wherein operating the electric motor includes receiving input from a second sensor that detects conditions other than an angular position of the rotor and factoring that input from the second sensor into imparting at least one of the command at least one of torque and velocity and the at least one of ripple torque and ripple velocity.
20 . The method of claim 1 , wherein the electric motor is a BLDC motor.
21 . The method of claim 1 , wherein the electric motor is immersed in a hydraulic fluid with the hydraulic pump.
22 . The method of claim 1 , wherein coupling the electric motor to the hydraulic pump comprises disposing the electric motor coaxially with the hydraulic pump.
23 . The method of claim 1 , wherein operating the electric motor comprises adjusting current flow through windings of the electric motor in response to the sensed angular position of the rotor of the electric motor.
24 . The method of claim 1 , wherein operating the electric motor comprises adjusting voltage in the windings of the electric motor in response to the sensed angular position of the rotor of the electric motor.
25 . The method of claim 1 , wherein operating the electric motor comprises receiving input from a plurality of feedback sensors that sense impact of the imparted at least one of torque and velocity on a hydraulic fluid that engages the hydraulic pump.
26 . A method of hydraulic ripple cancellation, comprising:
sensing an angular position of a rotor of an electric motor;
operatively coupling the electric motor to a hydraulic pump; and
operating the electric motor to comply with a at least one of torque and velocity control model of hydraulic pump that facilitates mitigation of hydraulic ripple associated with fluid flow and pressure changes during rotation of the hydraulic pump, based on the sensed angular position of the rotor.
27 . The method of claim 26 , wherein operating the electric motor comprises imparting a command at least one of torque and velocity on the hydraulic pump and imparting a at least one of ripple torque and ripple velocity on the hydraulic pump based at least in part on the sensed angular position of the rotor.
28 . The method of claim 27 , wherein the at least one of ripple torque and ripple velocity at least partially cancels hydraulic ripple associated with fluid flow and pressure changes.
29 . The method of claim 26 , wherein the control model comprises one of a function and a multidimensional array.
30 . The method of claim 26 , wherein the control model includes motor torque and speed as inputs.
31 . The method of claim 26 , wherein the control model adapts parameters based on one or more feedback sensors.
32 . The method of claim 31 , wherein the one or more feedback sensors comprises one of an accelerometer and a pressure sensor.
33 . A system comprising:
a motor controller adapted to dynamically control an electric motor that is operatively coupled to a hydraulic pump and adapted to receive a command input; and
a control algorithm that facilitates the motor controller determining a at least one of ripple torque and ripple velocity factor based on a detected position of a rotor of the electric motor, wherein the motor controller imparts at least one of torque and velocity control on the hydraulic pump through the electric motor, the at least one of torque and velocity control comprising a command input component and a at least one of ripple torque and ripple velocity component.
34 . The system of claim 33 , wherein the ripple component is at least one of a torque component and a velocity component.
35 . The system of claim 33 , wherein the command input component is at least one of a torque component and a velocity component.
36 . The system of claim 33 , wherein the hydraulic pump creates a hydraulic ripple comprising at least one of a pressure ripple and a fluid flow ripple, and the at least one of ripple torque and ripple velocity imparted on the hydraulic pump is substantially out of phase with the hydraulic ripple.
37 . The system of claim 33 , wherein the hydraulic pump is at a constant speed and is characterized by a varying flow rate with respect to angular position, and wherein at least one of torque and velocity of the electric motor is electrically controlled to compensate for this non-constant flow property.
38 . The system of claim 33 , wherein the at least one of ripple torque and ripple velocity is a variable of at least one of torque and velocity that is imparted based on at least one of current electric motor torque and current electric motor speed.
39 . The system of claim 33 , wherein the at least one of ripple torque and ripple velocity substantially comprises a periodic waveform.
40 . The system of claim 39 , wherein the periodic waveform comprises one or more sine waves.
41 . The system of claim 39 , wherein the periodic waveform comprises a plurality of waveforms, each having a period, magnitude, and shape.
42 . The system of claim 39 , wherein the periodic waveform at least partially cancels one or more harmonics of the hydraulic ripple.
43 . The system of claim 33 , wherein electric motor velocity is electrically varied based at least in part on the sensed angular position of the rotor.
44 . The system of claim 33 , further comprising a rotor position sensor that is one of a rotary magnetic/optical encoder and a Hall effect sensor.
45 . The system of claim 33 , further comprising a plurality of voltage and current sensors measuring currents and voltages of the electric motor, with an algorithm detecting rotor position using sensorless control.
46 . The system of claim 33 , wherein the at least one of ripple torque and ripple velocity is imparted based on a model of at least one of torque and velocity control.
47 . The system of claim 46 , wherein the model of at least one of torque and velocity is feed-forward.
48 . The system of claim 46 , wherein the model of at least one of torque and velocity adapts parameters based on one or more feedback sensors.
49 . The system of claim 48 , wherein the feedback sensor is one of an accelerometer and a pressure sensor.
50 . The system of claim 46 , wherein the model of at least one of torque and velocity control comprises one of a function and a multidimensional array.
51 . The system of claim 46 , wherein independent variables in the model comprise of at least one of rotor velocity, motor torque, and hydraulic pressure.
52 . The system of claim 46 , wherein the model of at least one of torque and velocity control outputs one or more magnitude and phase values that specify the ripple cancellation waveform.
53 . The system of claim 46 , wherein the model of at least one of torque and velocity control comprises a multidimensional array that represents at least one of ripple torque and ripple velocity parameters for a plurality of rotor speeds.
54 . The system of claim 33 , wherein operating the electric motor includes receiving input from a second sensor that detects conditions other than an angular position of the rotor and factoring that input from the second sensor into imparting at least one of the command at least one of torque and velocity and the at least one of ripple torque and ripple velocity.
55 . The system of claim 33 , wherein the electric motor is a BLDC motor.
56 . The system of claim 33 , wherein the electric motor is immersed in a hydraulic fluid with the hydraulic pump.
57 . The system of claim 33 , wherein coupling the electric motor to the hydraulic pump comprises disposing the electric motor coaxially with the hydraulic pump.
58 . The system of claim 33 , wherein operating the electric motor comprises receiving input from a plurality of feedback sensors that sense impact of the imparted at least one of torque and velocity on a hydraulic fluid that engages the hydraulic pump.
59 . A system comprising:
an electro-hydraulic actuator of a vehicle suspension system comprising a motor controller adapted to dynamically control an electric motor that is operatively coupled to a hydraulic pump and adapted to receive a command input; and
a control algorithm that facilitates the motor controller determining a ripple torque factor based on a detected position of a rotor of the electric motor, wherein the motor controller imparts at least one of torque and velocity control on the hydraulic pump through the electric motor, the at least one of torque and velocity control comprising a command component and a at least one of ripple torque and ripple velocity component.
60 . The system of claim 59 , wherein the command component is at least one of a torque component and velocity component.
61 . The system of claim 59 , wherein the ripple component is at least one of a torque component and a velocity component.
62 . The system of claim 59 , wherein the hydraulic pump creates a hydraulic ripple comprising at least one of a pressure ripple and a fluid flow ripple, and the at least one of ripple torque and ripple velocity imparted on the hydraulic pump is substantially out of phase with the hydraulic ripple.
63 . The system of claim 59 , wherein the hydraulic pump is at a constant speed and is characterized by a varying flow rate with respect to angular position, and wherein at least one of torque and velocity of the electric motor is electrically controlled to compensate for this non-constant flow property.
64 . The system of claim 59 , wherein the at least one of ripple torque and ripple velocity is a variable of at least one of torque and velocity that is imparted based on at least one of current electric motor torque and speed.
65 . The system of claim 59 , wherein the at least one of ripple torque and ripple velocity substantially comprises a periodic waveform.
66 . The system of claim 65 , wherein the periodic waveform comprises one or more sine waves.
67 . The system of claim 65 , wherein the periodic waveform comprises a plurality of waveforms, each having a period, magnitude, and shape.
68 . The system of claim 65 , wherein the periodic waveform at least partially cancels one or more harmonics of the hydraulic ripple.
69 . The system of claim 59 , wherein electric motor velocity is electrically varied based at least in part on the sensed angular position of the rotor.
70 . The system of claim 59 , further comprising a rotor position sensor that is one of a rotary magnetic/optical encoder and a Hall effect sensor.
71 . The system of claim 59 , further comprising a plurality of voltage and current sensors measuring currents and voltages of the electric motor, with an algorithm detecting rotor position using sensorless control.
72 . The system of claim 59 , wherein the at least one of ripple torque and ripple velocity is imparted based on a model of at least one of torque and velocity control.
73 . The system of claim 72 , wherein the model of at least one of torque and velocity is feed-forward.
74 . The system of claim 72 , wherein the model of at least one of torque and velocity adapts parameters based on one or more feedback sensors.
75 . The system of claim 74 , wherein the one or more feedback sensors comprises one of an accelerometer and a pressure sensor.
76 . The system of claim 72 , wherein the model of at least one of torque and velocity control comprises one of a function and a multidimensional array.
77 . The system of claim 72 , wherein independent variables in the model comprise of at least one of rotor velocity, motor torque, and hydraulic pressure.
78 . The system of claim 72 , wherein the model of at least one of torque and velocity control outputs one or more magnitude and phase values that specify the ripple cancellation waveform.
79 . The system of claim 72 , wherein the model of at least one of torque and velocity control comprises a multidimensional array that represents at least one of ripple torque and ripple velocity parameters for a plurality of rotor speeds.
80 . The system of claim 59 , wherein operating the electric motor includes receiving input from a second sensor that detects conditions other than an angular position of the rotor and factoring that input from the second sensor into imparting at least one of the command at least one of torque and velocity and the at least one of ripple torque and ripple velocity.
81 . The system of claim 59 , wherein the electric motor is a BLDC motor.
82 . The system of claim, wherein the electric motor is immersed in a hydraulic fluid with the hydraulic pump.
83 . The system of claim 59 , wherein coupling the electric motor to the hydraulic pump comprises disposing the electric motor coaxially with the hydraulic pump.
84 . The system of claim 59 , wherein operating the electric motor comprises receiving input from a plurality of feedback sensors that sense impact of the imparted at least one of torque and velocity on a hydraulic fluid that engages the hydraulic pump.
85 . A method of hydraulic ripple cancellation, comprising:
measuring a sensor that correlates with pressure ripple in a hydraulic system;
operatively coupling an electric motor to a hydraulic pump that induces the hydraulic ripple; and
operating the electric motor to impart a command at least one of torque and velocity component on the hydraulic pump and to impart a at least one of ripple torque and ripple velocity component on the hydraulic pump based at least in part on the sensed pressure ripple in the hydraulic system.
86 . The method of claim 85 , wherein the command component is at least one of a torque component and velocity component.
87 . The method of claim 85 , wherein the ripple component is at least one of a torque component and a velocity component.
88 . The method of claim 85 , wherein the sensor that correlates with pressure ripple comprises at least one of a pressure sensor, a flow rate sensor, a strain gauge, and an accelerometer disposed on the hydraulic system.