# US 5,708,334 A · Method for controlling an electric drive of a vehicle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,708,334 A - Document ID: US5708334A - Status: Granted - Kind: A - Application number: 08/596,913 - Filed: 1996-03-13 - Granted: 1998-01-13 - Earliest claimed: 1993-04-21 - Assignees: ABB Research Ltd. - Inventors: Rolf Schreiber; Rudiger Kogel; Peter Hildenbrand - Web page: https://patentgrep.com/patent/US5708334A ## CPC - B60L 3/10: Indicating wheel slip {; Correction of wheel slip} - B60L 2200/26: Rail vehicles - Y02T 10/72: Electric energy management in electromobility - 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 - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A method for open-loop and closed-loop control of an electric drive of a vehicle, in particular of a rail vehicle, utilizes a frictional engagement between a wheel and a rail or an underlying surface, to a high degree. A control is carried out which takes into account a gradient of a characteristic frictional engagement line. The system operates with a substitute variable for the gradient, which can be detected by a technical measurement, and a set torque value which is prescribed by the operator being limited in such a way that a travel/braking mode is achieved at an optimum, prescribed operating point of the characteristic frictional engagement line. ## Claims ### Claim 1 A method of controlling a drive of a vehicle, wherein a setpoint torque is prescribed for the drive of the vehicle, the method which comprises: reducing a setpoint torque prescribed for a drive of a vehicle to an input torque which allows an operation of the vehicle substantially at a maximum frictional engagement between the vehicle wheel and an underlying surface; wherein the step of reducing includes: a) continuously determining a curve representing a current frictional engagement between the vehicle wheel and the underlying surface; b) measuring a substitute variable having a defined physical relationship with a gradient of the curve, and determining the gradient of the curve from the substitute variable; c) forming a reduction factor from a difference between a current gradient of the curve and a predetermined set-point gradient; and d) forming the input torque by multiplying the setpoint torque with the reduction factor. ### Claim 2 (depends on 1) The method according to claim 1, wherein the substitute variable is a phase shift signal determined as follows: a) superimposing a test signal on the set input torque value; b) measuring angular speed or angular acceleration at a mechanical output; c) filtering out an output-side test signal contained in a measurement signal obtained in the step of measuring; d) comparing an input-side test signal and the output-side test signal and determining their phase shift, and using their phase shift as the substitute variable; and e) using a test signal which is known to have an unambiguous relation between phase shift and gradient of the curve. ### Claim 3 (depends on 2) The method according to claim 2, wherein the superimposing step comprises superimposing a sinusoidal test signal on the setpoint torque. ### Claim 4 (depends on 2) The method according to claim 2, which comprises measuring the angular speed or angular acceleration at the mechanical output at an engine shift of the electric drive. ### Claim 5 (depends on 1) The method according to claim 1, which comprises forming the reduction factor with a control device having integral characteristics. ### Claim 6 (depends on 5) The method according to claim 5, which comprises forming the reduction factor with a PI controller. ### Claim 7 (depends on 1) The method according to claim 1, which comprises raising a set value of the substitute variable with the aid of a modified actual value of the substitute variable, and forming the modified actual value by differentiation of the actual value with subsequent limiting on one side. ### Claim 8 (depends on 1) The method according to claim 1, wherein step a) includes determining the curve from a coefficient of friction taken as a function of a slip between the wheel and the underlying surface. ### Claim 9 A method of controlling a drive of a rail vehicle of the type having wheels supported on rails and a car supported on the wheels, an electric drive motor powering the wheels, and wherein a setpoint output torque is prescribed by an operator of the rail vehicle for the electric drive motor, the method which comprises: reducing a setpoint torque prescribed for the electric drive motor of the rail vehicle to an input torque which allows an operation of the rail vehicle substantially at a maximum frictional engagement between the wheel and the underlying rail; wherein the step of reducing includes: a) continuously determining a curve representing a current frictional engagement between the vehicle wheel and the underlying rail; b) measuring a substitute variable having a defined physical relationship with a gradient of the curve, and determining the gradient of the curve from the substitute variable; c) forming a reduction factor from a difference between a current gradient of the curve and a predetermined set-point gradient; and d) forming the input torque by multiplying the setpoint torque with the reduction factor.