Valve, controller, system and method providing closed loop current control of a voice coil using pulse width modulation drive elements

Abstract

A linear voice coil actuator is described, specifically applied to a fluid power valve. The valve includes at least one inlet port and at least one outlet port. A spool controls fluid flow between the inlet port and outlet port. At least one counter-acting spring asserts a force on the spool. The valve also includes a linear voice coil to regulate movement of the spool. The linear voice coil responds to a pulse width modulated signal, wherein the pulse width modulated signal is based on a determined current in the linear voice coil. Electromagnetic interference filtering may also be used. A controller, system and method are also described.

1 . A valve comprising:
 at least one inlet port;   at least one outlet port;   a spool configured to control fluid flow between the inlet port and outlet port;   at least one counter-acting spring configured to assert a force on the spool; and   a linear voice coil configured to regulate movement of the spool;   wherein the linear voice coil is configured to respond to a pulse width modulated signal, wherein the pulse width modulated signal is based on at least a determined current in the linear voice coil.   
   
   
       2 . The valve of  claim 1 , wherein the pulse width modulated signal minimizes voltage and current ripples in the linear voice coil. 
   
   
       3 . The valve of  claim 1 , wherein providing the pulse width modulation drive signal uses an H-bridge topology that allows for bi-directional drive currents. 
   
   
       4 . The valve of  claim 1 , wherein a switching frequency of the pulse width modulation drive signal is between about 20 kHz and about 1 MHz. 
   
   
       5 . A controller comprising:
 a receiver configured to receive a current signal based upon a determined current through a linear voice coil; and   a processor configured to produce a control signal based on at least the received current signal, wherein the control signal is to be used by a pulse width modulation driver to generate a pulse width modulation drive signal to be applied to the linear voice coil.   
   
   
       6 . The controller of  claim 5 , further comprising electromagnetic interference filter circuitry configured to minimize voltage and current ripples in the linear voice coil. 
   
   
       7 . The controller of  claim 5 , wherein generating the pulse width modulation drive signal uses an H-bridge topology that allows for bi-directional drive currents. 
   
   
       8 . The controller of  claim 5 , wherein a switching frequency of the pulse width modulation drive signal is between about 20 kHz and about 1 MHz. 
   
   
       9 . A system comprising:
 a linear voice coil actuated valve comprising: a spool; at least one counter-acting spring configured to apply a force on the spool; and a linear voice coil configured to regulate a fluid flow through the valve by moving the spool;   a sensor configured to determine a current in the linear voice coil;   a processor configured to produce a control signal based at least on the determined current; and   a pulse width modulation driver responsive to the control signal configured to generate a pulse width modulation drive signal to be applied to the linear voice coil.   
   
   
       10 . The system of  claim 9 , further comprising electromagnetic interference filter circuitry configured to minimize voltage and current ripples in the linear voice coil. 
   
   
       11 . The system of  claim 9 , wherein the sensor comprises at least one of a Hall Effect current sensor, a toroidal Hall Effect sensor, current sense resistors, and transformers. 
   
   
       12 . The system of  claim 9 , wherein the sensor further comprises a difference amplifier circuit. 
   
   
       13 . The system of  claim 13 , wherein the difference amplifier circuit has a common mode rejection ratio of at least −40 dB. 
   
   
       14 . The system of  claim 13 , wherein common mode rejection ratio limits are applied at least to a fifth harmonic of the pulse width modulation drive signal. 
   
   
       15 . The system of  claim 9 , wherein generating the pulse width modulation drive signal uses an H-bridge topology that allows for bi-directional drive currents. 
   
   
       16 . The system of  claim 9 , wherein a switching frequency of the pulse width modulation drive signal is between about 20 kHz and about 1 MHz. 
   
   
       17 . A method comprising:
 providing a pulse width modulation drive signal to a linear voice coil of a linear voice coil actuated valve;   determining a current through the linear voice coil; and   adjusting the pulse width modulation drive signal based at least upon the determined current;   wherein the linear voice coil is used to move a spool having a force applied to the spool by at least one counter-acting spring.   
   
   
       18 . The method of  claim 17 , further comprising an electromagnetic interference filter designed to minimize voltage and current ripples in the linear voice coil in order to produce less electromagnetic radiation. 
   
   
       19 . The method of  claim 17 , wherein determining the current comprises using at least one of a Hall Effect current sensor, a toroidal Hall Effect technique, current sense resistors, and transformers. 
   
   
       20 . The method of  claim 17 , wherein providing the pulse width modulation drive signal uses an H-bridge topology that allows for bi-directional drive currents.