Patent Publication Number: US-10783922-B2

Title: Motor spin up with auxiliary power boost

Description:
RELATED APPLICATION 
     This is a continuation application claiming the benefit of priority to U.S. non-provisional application Ser. No. 14/704,588, which issues as U.S. Pat. No. 10,229,710 on Mar. 12, 2019. 
    
    
     SUMMARY 
     Some embodiments of the present technology contemplate an apparatus having a data storage disc and a motor supporting the disc in rotation. Control circuitry operates to spin up the disc drive by accelerating the motor to a steady state speed by: beginning the spin up by energizing the motor with a primary power; comparing an amount of auxiliary power that is available from a battery to a predefined threshold; and before the motor is accelerated to the steady state speed and if the threshold comparison is favorable, then boosting the primary power by discharging the battery for a predetermined boost interval. 
     Some embodiments of the present technology contemplate an apparatus having a battery, a data storage disc, and a motor supporting the disc in rotation. Control circuitry operates to compare an amount of auxiliary power that is available from the battery to a predefined threshold, and if the threshold comparison is favorable then boost a primary power to the motor by discharging the battery for a predetermined boost interval. 
     Some embodiments of this technology contemplate a method characterized by steps of: obtaining a data storage device having a battery, a data storage disc, and a motor operably supporting the disc in rotation; accelerating the motor to a predetermined steady state speed; comparing an amount of auxiliary power that is available from the battery to a predefined threshold; and if the comparing step satisfies the threshold requirement, then during the accelerating step boosting a primary power to the motor by discharging the battery. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a plan view of a disc drive data storage device that is constructed in accordance with embodiments of the present technology. 
         FIG. 2  depicts a block diagram of the control system in the disc drive of  FIG. 1 . 
         FIG. 3  depicts a block diagram of the motor control circuitry in the control system of  FIG. 2 . 
         FIG. 4  depicts a block diagram of the power boosting circuitry in the disc drive of  FIG. 1 . 
         FIG. 5  depicts a graphical comparison of a spin up using the boost power of this technology to a spin up not using the boost power of this technology. 
         FIG. 6  depicts a flowchart of steps in a method for MOTOR SPIN UP in accordance with embodiments of this technology. 
         FIG. 7  depicts a block diagram of alternative embodiments of the power boosting circuitry of  FIG. 4 . 
         FIG. 8  depicts a block diagram of alternative embodiments in which the disc drive of  FIG. 1  is included in a storage array within a wide area network computer system. 
         FIG. 9  depicts a block diagram of the storage array of  FIG. 8 . 
         FIG. 10  depicts a block diagram of alternative embodiments in which the power boost circuitry resides externally to the disc drive. 
     
    
    
     DETAILED DESCRIPTION 
     Initially, it is to be appreciated that this disclosure is by way of example only, not by limitation. The power concepts herein are not limited to use or application with any specific system or method. Thus, although the instrumentalities described herein are for the convenience of explanation, shown and described with respect to exemplary embodiments, it will be appreciated that the principles herein may be applied equally in other types of systems and methods involving spinning up an electric motor. 
     The present disclosure generally relates to the design and control of electronic circuitry that is employed to spin up a motor. By “spin up” it is meant the process of starting the motor from rest or from a reduced speed and accelerating it to an operational, steady state speed. The interval of time necessary to spin up the motor is referred to herein as the time to ready (TTR). A primary power supply is boosted by inclusion of an auxiliary power to shorten the TTR. 
     Embodiments of the technology are described herein as practically applied to spinning up a motor in a disc drive data storage device, although the contemplated embodiments are not so limited. In equivalent alternative embodiments the motor can be something other than a disc drive motor. From reading the disclosure herein of the illustrative embodiments, the skilled artisan does not need an enumeration of all types of motor systems that are suited for using this technology in order to understand the scope of the claimed subject matter, and so no such enumeration is attempted. 
     For purposes of these illustrative embodiments,  FIG. 1  provides a top plan view of a data storage device in the form of a disc drive  100  that is constructed in accordance with illustrative embodiments of the present technology. A base deck  102  and a top cover  104  (shown in partial cutaway) cooperate to form a sealed housing for the disc drive  100 . A spindle motor  106  rotates one or more magnetic recording discs  108 . An actuator assembly  110  supports an array of read/write heads  112  adjacent the respective disc surfaces. The actuator assembly  110  is rotated through the application of current to a voice coil motor (VCM)  116 . 
     The spindle motor  106  in a high capacity disc drive  100  rotates a stack of discs  108 . The additional mass of six discs  108 , for example, requires more electrical energy to spin up in the same TTR in comparison to another disc drive  100  having only one disc  108 . However, cost constraints and power budgets prevent outright sizing the motor and/or power supply large enough to equalize the TTR performance of low and high capacity disc drives  100 . However, reducing the TTR in high capacity disc drives  100  would be advantageous in providing faster data access to the end-user. It is to technological solutions of that problem that the embodiments of this technology are directed. 
       FIG. 2  is a block depiction of relevant portions of a control circuit controlling operation of the disc drive  100  of  FIG. 1 . Position-controlling of the read/write head(s)  112  is provided by a servo control circuit  118  that is programmed with computer code to form a servo control loop. The servo control circuit  118  generally includes a controller  120 , a memory such as the random access memory (RAM)  122  depicted, a demodulator (DEMOD)  124 , and a motor control circuit  126 . Certain details are known to the skilled artisan and thus not depicted. For example, typically the controller  120  can include a general purpose processor in conjunction with an application specific integrated circuit (ASIC) hardware-based servo controller. 
       FIG. 3  is a block depiction of relevant portions of the motor control circuitry  126  of  FIG. 2 . Control logic  128  receives commands from, and outputs state data to, the controller  120 , and controls operation of the motor  106  during transitional operations (referred to as spin up and spin down) and steady-state operations. The control logic  128  includes spin up boost logic  130  that operably decreases the motor  106 &#39;s spin up cycle time (TTR) in accordance with this technology. Spindle driver circuitry  132  applies drive currents to the phases of the spindle motor  106  over a number of sequential commutation steps to rotate the motor  106 . During each commutation step, current is applied to one phase, sunk from another phase, and a third phase is held at a high impedance in an unenergized state. Back electromagnetic force (bemf) detection circuitry  134  measures the bemf generated on the unenergized phase, compares this voltage to the voltage at a center tap, and outputs a zero crossing (ZX) signal when the bemf voltage changes polarity with respect to the voltage at the center tap. A commutation circuit  136  uses the ZX signals to generate and output commutation timing (CT) signals to time the application of the next commutation step. 
       FIG. 4  is a block depiction more particularly detailing implementation of the reduced TTR of this technology. In these illustrative embodiments the components reside within the disc drive  100 , interconnected via its printed circuit board assembly (PCBA)  138 . However, the contemplated embodiments are not so limited. In alternative embodiments discussed below some of the components and circuitry can reside outside the disc drive  100 , between it and the external source of power. 
     A power supply  140  operably receives input alternating current (AC) power from the source of power (not shown) and outputs various associated direct current (DC) voltages on different supply paths, such as the path  142 . For the sake of an illustrative description entirely, without limitation, the output voltage from the power supply  140 , herein referred to as the “supply power,” can be provided at a nominal value such as twelve volts (12V). This supply power is supplied through protection diode  143  to a regulator  144  which applies voltage regulation to provide an output regulated voltage to path  146 . The regulated voltage passes to the motor  106 , a ground connection  148  denoting the completion of this primary supply power loop. An analog to digital converter (“ADC”)  150  provides to the spin up boost logic  130  a digital indication of the supply power. For example, without limitation, the ADC  150  can include an ammeter informing the spin up boost logic  130  of the amount of current supplied to the motor  106 . 
     A recharge circuit  152  receives input voltage from the power supply  140  via path  154  to selectively apply recharging current to a rechargeable battery  156 , via path  158 . For purposes of this description and meaning of the claims, a “rechargeable battery” or “battery” herein means a type of electrical battery that stores energy through a reversible electrochemical reaction and can be electrically charged, discharged to an electrical load, and then recharged, many times over. Several different combinations of electrode materials and electrolytes are suitable for constructing the rechargeable battery in this technology, including but not limited to at least nickel metal hydride, lithium ion, lithium ion polymer, and the like. The battery  156  is selectively used to supplement the primary power to the motor  106  with an auxiliary power boost for a predetermined time during spin up of the motor  106 . 
     The battery  156  supplies the auxiliary power on path  160 . Another ADC  162  provides to the spin up boost logic  130  a digital indication of the available auxiliary power (depending on the present charge state of the battery  156 ). For example, without limitation, the ADC  162  can include an ammeter informing the spin up boost logic  130  of the amount of current that is discharged from the battery  156 . During normal operation, path  160  is preferably decoupled from path  142  (i.e., spin up boost logic  130  opens switching element  164 ) so that the regulator  144  receives power from only the power supply  140 . The switching element  164  can be constructed of a suitable transistor, one or more protection diodes, etc., as desired. 
       FIG. 5  graphically depicts a typical spin up velocity curve  166  for the motor  106 , from a zero velocity at time t 0  to a steady state velocity at time t TTR  (“Time to Ready”). The curve  166  has an initial trajectory during open loop acceleration from t 0  to an intermediate velocity V I  at time t I , and then another trajectory during closed loop acceleration from t I  to the t TTR . Both trajectories in these illustrative embodiments are linear, although the contemplated embodiments are not so limited in that they can be partially or entirely nonlinear. 
       FIG. 6  depicts a graphical comparison of a spin up velocity curve  168  of this technology to a spin up velocity curve  166  of disc drive not using the boost power of this technology. The velocity curves are plotted from a zero velocity at time t 0  to a steady state velocity at time t TTR  (“time to ready”). The curves  166 ,  168  have an initial trajectory during open loop acceleration from t I  to an intermediate velocity V I  at time t 1 . In these illustrative embodiments the curves  166 ,  168  have different trajectories during closed loop acceleration from t I  to the corresponding t TTR . Both trajectories in these illustrative embodiments are linear, although the contemplated embodiments are not so limited in that they can be partially or entirely nonlinear. 
     Curve  168  depicts at time t I  the spin up boost logic  130  ( FIG. 4 ) can close the switching element  164  to boost the power from the power supply  140  by the inclusion of the auxiliary power from the battery  156 . The increased trajectory of the curve  168  results in a significantly reduced time required to reach the V TTR . In alternative embodiments (not depicted) the spin up boost logic  130  can close the switching element  164  at time t 0  to boost the power to the motor  106  substantially simultaneously to the initial open loop acceleration of the motor  106 . 
       FIG. 6  is a flowchart depicting steps in a method  200  for MOTOR SPIN UP performed by computer execution of boost spin up logic (such as  130 ) in accordance with illustrative embodiments of the present invention. The method begins in block  202  with the controller (such as  120  depicted in  FIG. 2 ) detecting a device enable (“EN”) signal from the host device. The EN signal is employed in these illustrative embodiments to spin up the motor (such as  106 ) to the steady state speed, at a time when the power to the motor has been reduced or shut off during reduced activity or inactivity. 
     In block  204  the spin up boost logic determines whether the battery (such as  156 ) is presently storing enough power to provide the boost of start up power needed to significantly reduce the TTR. For example, without limitation, during reduction to practice it was empirically determined that reducing the TTR required boosting the supply power with an auxiliary power (from the battery) of two amperes at twelve volts and for eight seconds. The energy required from the auxiliary power is:
 
 E= 2 amps*12 volts*8 seconds=53mAh
 
     If the battery has been used repeatedly in numerous spin up cycles and not yet recharged, then the determination of block  204  can be “no.” In that case, control passes to block  206  where the disc drive  100  spins up the motor with only the primary supply power, forgoing the reduced TTR benefits of this technology. If, contrarily, the determination of block  206  is “yes,” then in block  208  the spin up boost logic computes a boost interval during which the switching element  164  is to be closed in order to provide the desired boost during the spin up. In some embodiments the boost interval can be a predetermined interval of elapsed time. For example, the spin up boost logic can define the interval as beginning at the intermediate interval of time t I  and last for a duration of the eight seconds used in the example above. Alternatively, the spin up boost logic can define the boost interval in terms of a voltage drop from an initial voltage of the battery at the beginning of the interval to a predetermined reduced voltage. 
     After the boost interval is predefined, and at the beginning of the predefined boost interval, in block  210  the spin up boost logic closes the switching element to begin boosting the spin up power. In block  212  it is determined whether the boost interval is completed. If the determination of block  212  is “yes,” then in block  214  the spin up boost logic opens the switching element to end boosting the spin up power. 
     In block  216  it is determined whether to recharge the battery or not. First, that determination is delayed until a predetermined time has elapsed after the switching element is opened in block  214 . For example, the spin up boost logic can proceed in response to a timer that is started in conjunction with actuation of the switching element in block  210 . The timer can start with the closing of the switching element at the beginning of the boosting, or the timer can start with the opening of the switching element at the end of the boosting. For another example, the spin up boost logic can proceed in response to the power (in terms of current) to the motor dropping below a predetermined value after the boosting is ended. In either case, the momentary delay before recharging, when recharging occurs, ensures not overloading the external power supply by the boosting and recharging duties. 
     After the delay, the spin up boost logic then determines if the battery has been sufficiently discharged to warrant a call to the recharge circuit (such as  152 ) to begin recharging the battery to a maximum power. That determination can be based on a comparison of the battery&#39;s stored energy to a preselected threshold value, such as 80% of battery capacity. If the determination of block  216  is “yes,” then the battery is recharged to completion in blocks  218 ,  220 . 
     The embodiments depicted in  FIG. 4  describe only one 12V power channel for powering the high voltage components, such as the motor  106 , although the contemplated embodiments are not so limited.  FIG. 7  depicts alternative embodiments in which the disc drive  100  also has a reduced voltage (such as 5V) power channel for powering low voltage components, such as the control electronics. In a similar fashion described above, the battery and associated circuitry is configured to share the battery&#39;s auxiliary power with each of the power channels. Alternatively, each power channel can be provided with a dedicated battery. The spin up boost logic  130  individually controls a switching element for each power channel so that boosting the primary power in one of the power channels can be done independently of boosting the primary power in the other power channel. 
     Furthermore, although the illustrative embodiments emphasize the use of primary and auxiliary power to energize just the motor  106 , the contemplated embodiments are not so limited. The embodiments of this technology contemplate circuitries providing the primary and auxiliary power to service the entire electrical requirements (high voltage and low voltage requirements) of the disc drive  100 . 
     The embodiments discussed so far are related to the battery and associated circuitry residing within the disc drive  100 ; in alternative embodiments they can reside outside the disc drive  100 . For example,  FIG. 8  depicts pluralities of the disc drives  100  employed to form storage arrays  222   A ,  222   B  in a computer-based system  224  characterized as a wide area network (WAN). The system  224  includes a number of host computers  226 , respectively identified as hosts A, B and C. The host computers  226  interact with each other as well as with the data storage arrays  222   A ,  222   B  via a fabric  228 . The fabric  228  is preferably characterized as a fibre-channel based switching network, although other configurations can be utilized as well including the Internet. It is contemplated that the host computer  226   A  and the data storage array  222   A  are physically located at a first site, the host computer  226   B  and the storage array  222   B  are physically located at a second site, and the host computer  226   C  is at yet a third site, although such is merely illustrative and not limiting. 
     As shown in  FIG. 9 , the storage array  222   A  can include a pair of controllers  228   A1 ,  228   A2  and an array of the data storage devices  100 . The controllers  228  and data storage devices  100  preferably utilize a fault tolerant arrangement so that the various controllers  228  utilize parallel, redundant links and at least some of the user data stored by the system  222  is mirrored, either within the same storage array  222  or distributed among different storage arrays  222 . Each array  222  further includes a pair of power modules  230   A1 ,  230   A2  that supply electrical power to the controllers  228  and the data storage devices  100 . The power modules  230  are preferably configured to operate in tandem so that during normal operation the power module  230   A1  supplies power to the controller  228   A1  and to half of the data storage devices  100 , and the power module  230   A2  supplies power to the controller  228   A2  and to the other half of the data storage devices  100 . Each power module  230  can further be sized and configured to be able to individually supply all of the power for the array  222  should the other power module  230  become inoperative.  FIG. 10  depicts relevant portions of one of the power modules  230  of  FIG. 10  in accordance with these alternative embodiments of the present invention. The components in the power module  230  are similar to the embodiments of  FIG. 4  described above, and as such retain like reference numbers here where they reside outside the disc drive  100  between it and the external source of supply power (not depicted). 
     In yet other embodiments of this technology the components in  FIG. 10  (battery, recharging module, circuitry) can be constructed to reside in a portable module that is removably pluggable into a device. For example, without limitation, the portable module can be pluggable into a communications port in the power module  230 , in the disc drive  100 , or in the interconnecting power cabling and/or adapter between the power module  230  and the disc drive  100 . For example, the portable module can provide the boosted TTR advantages of this technology to an existing product by plugging into the system by the product&#39;s universal serial bus (USB) port. 
     It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. In addition, although the embodiments described herein are directed to data storage devices, it will be appreciated by those skilled in the art that the claimed subject matter is not so limited and various other systems that spin up a motor can utilize the embodiments of this technology without departing from the spirit and scope of the claimed invention.