# US 10,246,266 B2 · Method for controlling the normal force of a transport unit of a long stator linear motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,246,266 B2 - Document ID: US10246266B2 - Status: Granted - Kind: B2 - Application number: 15/926,334 - Filed: 2018-03-20 - Published: 2018-09-27 - Granted: 2019-04-02 - Earliest claimed: 2017-03-21 - Assignees: B&R Industrial Automation GmbH - Applicants: B&R Industrial Automation GmbH - Inventors: Andreas Weber; Franz Spanlang - Web page: https://patentgrep.com/patent/US10246266B2 ## CPC - B65G 43/02: detecting dangerous physical condition of load carriers, e.g. for interrupting the drive in the event of overheating - B60L 13/03: Electric propulsion by linear motors - B60L 13/08: for the lateral position - B65G 54/02: electrostatic, electric, or magnetic - H02P 25/064: of the synchronous type - B65G 2203/02: Control or detection - H02P 6/006: {Controlling linear motors} - B65G: TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS (packaging B65B; handling thin or filamentary materials, e.g. paper sheets or thread, B65H; cranes B66C; portable mobile or lifting or hauling appliances, e.g. hoists, B66D; devices for lifting or lowering goods for loading or unloading purposes, e.g. fork-lift trucks, B66F9/00; emptying bottles, jars, casks, barrels or similar containers, not otherwise provided for, B67C9/00; delivering or transferring liquids B67D; filling or discharging vessels for liquefied, solidified or compressed gases F17C; pipe-line systems for fluids F17D) - B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract To reduce mechanical loading due to guidance of the transport unit of a conveyor installation in the form of a long stator linear motor and nevertheless ensure safe retention of the transport unit on the conveyor track of the conveyor installation in all operating conditions, the normal force (FNn) is controlled with a controller (Rk) for controlling the normal force (FNn). The controller (Rk) determines a normal-force-forming current component (iAnd) of the drive current (iAn) of the drive coils interacting with the transport unit (Tn) so that a resulting normal force (FΣNn) acting on the transport unit (Tn) as the sum of the normal force (FNn), a magnetic force (FMn) in the normal direction (N) caused by the drive magnets, and an external force (FEn) in the normal direction (N) acting on the transport unit (Tn) corresponds at least to a specified retaining force (FNnmin) in the normal direction (N). ## Claims ### Claim 1 A method for controlling a normal force (FNn) acting on a transport unit of a conveyor installation in the form of a long stator linear motor on a track section of a conveyor track defined by the conveyor installation, on which track section drive coils of the long stator linear motor are provided on only one side of the transport unit and the transport unit is retained on the conveyor track on this side by guide elements, wherein a number of drive magnets on the transport unit interacts with a number of drive coils for generating the normal force (FNn) and the normal force (FNn) is controlled with a controller for controlling the normal force (FNn), wherein the controller determines a normal-force-forming current component of the drive current of the drive coils interacting with the transport unit so that a resulting normal force (FΣNn) acting on the transport unit as the sum of the normal force (FNn), a magnetic force (FMn) in a normal direction caused by the drive magnets, and an external force (FEn) in the normal direction acting on the transport unit corresponds at least to a specified retaining force (FNnmin) in the normal direction. ### Claim 2 (depends on 1) The method according to claim 1, wherein the controller for controlling the normal force (FNn) determines the normal-force-forming current component of the drive current from a known functional relationship between the normal-force-forming current component of the drive current and a setpoint value. ### Claim 3 (depends on 2) The method according to claim 2, wherein a setpoint flux is specified as the setpoint value, and the normal-force-forming current component is calculated as a quotient of the setpoint flux and a known inductance in the normal direction. ### Claim 4 (depends on 1) The method according to claim 1, wherein, in the controller for controlling the normal force (FNn), the normal-force-forming current component is determined from a difference between a setpoint value and an actual value by way of a normal-force controller. ### Claim 5 (depends on 1) The method according to claim 1, wherein, in the controller for controlling the normal force (FNn), a pilot current is determined by a pilot control from a setpoint value, and a control current is determined by a normal-force controller from a difference between the setpoint value and an actual value, and the normal-force-forming current component is determined as a sum of the pilot current and the control current. ### Claim 6 (depends on 5) The method according to claim 5, wherein the pilot current is determined based on a known relationship of a position of the transport unit relative to the conveyor track. ### Claim 7 (depends on 1) The method according to claim 1, wherein a forward-force-forming current component is determined in a controller for controlling a forward force (Fvn) of the transport unit and a drive current of the drive coils interacting with the transport unit is determined as a vectorial sum of the forward-force-forming current component and the normal-force-forming current component and the drive current is converted into coil voltages which are applied to the drive coils interacting with the transport unit.