ELECTRIC POWER STEERING SYSTEM AND CONTROL METHOD FOR IT AND VEHICLE WITH THIS SYSTEM

Abstract

An electric power steering system, a control method for it, and a vehicle equipped with it can enable two independent electronic control units to operate continuously by obtaining power from another power supply when the power supply to one of the two independent electronic control units is interrupted or a fault occurs in the power supply connected to one of the two independent electronic control units.

Description

REFERENCE TO A RELATED APPLICATIONThis application claims priority to Korean Patent Application No. 10-2024-0100935, filed on Jul. 30, 2024, which is hereby incorporated by reference for all purposes as if fully set forth herein.TECHNICAL FIELDAn embodiment of the present disclosure relates to a technology for supplying power between two independent electronic control units.BACKGROUNDIn general, an electric power steering system of a vehicle may refer to a system capable of changing the steering angle of the wheels based on a steering force (or rotational force) applied to a steering wheel by the driver.Recently, the electric power steering system may be configured with a redundant structure using two independent sensors and two independent electronic control units (ECUs) for controlling two independent actuators.That is, the electric power steering system may be configured such that even if one electronic control unit malfunctions, the other electronic control unit can operate normally.In this case, in the event of a fault in one of the two power supply units, two sensors and two electronic control units, the other electronic control unit can actuate the connected actuator in order to continue the steering operation.However, when the steering is continuously performed by an actuator, there is a problem that reliability and stability due to power loss can be reduced.ABORTEmbodiments of the present disclosure are intended to provide a manner that enables stable power supply to two independent electronic control units.According to an aspect of the present disclosure, there can be provided an electric power steering system including a first electronic control unit configured to convert a first voltage output from a first power supply into a first constant frequency pulse, output the first pulse to a first steering motor, and output a voltage lower than the first voltage output from the first power supply to a first external sensor, a second electronic control unit configured to convert a second voltage output from a second power supply into a second constant frequency pulse, output the second pulse to a second steering motor, and output a voltage lower than the second voltage output from the second power supply to a second external sensor, and a converter configured to, when a failure occurs in the first or second power supply, supplying a power supplied from another one of the first or second power supplies in which the failure does not occur to one of the first electronic control unit or the second electronic control unit in which the power supply from the first or second power supply is interrupted.According to another aspect of the present disclosure, there can be provided a method of controlling an electric power steering system, the method including converting, by a first electronic control unit, a first voltage output from a first power supply into a first constant frequency pulse, outputting the first pulse to a first steering motor, and outputting a voltage lower than the first voltage output from the first power supply to a first external sensor, and converting, by a second electronic control unit, a second voltage output from a second power supply into a second constant frequency pulse, outputting the second pulse to a second steering motor, and outputting a voltage lower than the second voltage output from the second power supply to a second external sensor, and supplying power generated from another one of the first and second power supplies in which the failure does not occur through a converter when a failure occurs in the first or second power supplies to one of the first electronic control unit and the second electronic control unit in which the power supply is interrupted from the first or second power supplies.According to another aspect of the present disclosure, there may be provided a vehicle including a first power supply configured to supply a first DC voltage, a first torque sensor and a first angle sensor, a first electronic control unit configured to convert the first DC voltage output from the first power supply into a first pulse having a constant frequency, output the first pulse to a first steering motor, and output a voltage lower than the first DC voltage output from the first power supply to the first torque sensor and the first angle sensor, a second power supply configured to supply a second DC voltage, a second torque sensor, and a second angle sensor, a second electronic control unit configured to convert the second DC voltage output from the second power supply into a second pulse having a constant frequency, outputting the second pulses to a second steering motor and outputting a voltage lower than the second DC voltage output from the second power supply to the second torque sensor and the second angle sensor, and a converter configured to, when a failure occurs in one of the first power supply or the second power supply, supply a power supplied from another one of the first power supply or the second power supply in which the failure does not occur to one of the first electronic control unit or the second electronic control unit in which the power supply from the one of the first power supply or the second power supply is cut off.According to an embodiment of the present disclosure, it is possible to provide a manner that enables stable power supply to two independent electronic control units.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a block diagram showing a vehicle equipped with an electric steering system according to the present embodiment. FIG. 2 is a block diagram illustrating an electric steering system according to an embodiment. FIGS. 3 and 4 are circuit diagrams illustrating an electric steering system according to an embodiment. FIG. 5 is a block diagram showing an electric steering system according to another embodiment. FIGS. 6 and 7 are circuit diagrams illustrating an electric steering system according to another embodiment. FIG. 8 is a block diagram showing an electric steering system according to another embodiment. FIG. 9 is a flowchart illustrating a control method for an electric steering system according to the present embodiment.DETAILED DESCRIPTIONIn the following description of examples or embodiments of the present disclosure, reference is made to the accompanying drawings, in which specific examples or embodiments that may be implemented are shown for illustration purposes and in which the same reference numerals and characters may be used to refer to the same or similar components, although shown in mutually different accompanying drawings. Further, in the following description of examples or embodiments of the present disclosure, detailed descriptions of known functions and components included herein have been omitted in some embodiments of the present disclosure when it has been found that the description may rather obscure the subject matter. The terms such as "including", "having", "containing", "consisting of", "made of", and "formed of" used herein are generally intended to allow the addition of other components unless the terms are used with the term "only". As used herein, singular forms are intended to include plural forms, unless the context clearly indicates otherwise.Terms such as "first", "second", "A", "B", "(A)", or "(B)" may be used herein to describe elements of the disclosure. Neither of these terms is used to define an importance, order, sequence, or number of elements, etc., but are used merely to distinguish the corresponding element from other elements.When it is said that a first element may be "connected or coupled to", "contacted or overlapped", etc., a second element is to be construed so that the first element may be not only "directly connected or coupled to" or "directly contacting or overlapped" with the second element, but also a third element may be "interposed" between the first and second elements, or the first and second elements may be "connected or coupled" or "contacting or overlapped" with each other via a fourth element. Here, the second element may be included in at least one of the two or more elements that are "connected or coupled to", "in contact or overlap", and so on.When time-related terms such as "after", "subsequent to", "following", "before", and the like are used to describe processes or sequences of the elements or configurations, or sequences or steps in operation, processing, manufacturing methods, these terms are used to describe non-consecutive or non-sequential processes or sequences unless the term "direct" or "immediate" is used herein.When dimensions, relative sizes, etc. are mentioned, it is also to be appreciated that numerical values for an element or features or corresponding information (e.g., degree, range, etc.) include a tolerance or range of errors that may be caused by various factors (e.g., process factors, internal or external influences, noise, etc.), even though a relevant description is not specified. Further, the term "could" may include all meanings of the term "may".FIG. 1 is a block diagram showing a vehicle equipped with an electric steering system according to the present embodiment, FIG. 2 is a block diagram showing an electric steering system according to one embodiment, FIGS. 3 and 4 are circuit diagrams showing an electric steering system according to one embodiment, FIG. 5 is a block diagram illustrating an electric steering system according to another embodiment, FIGS. 6 and 7 are circuit diagrams illustrating an electric steering system according to another embodiment, FIG. 8 is a block diagram illustrating an electric steering system according to another embodiment, and FIG. 9 is a flowchart illustrating a control method of an electric steering system according to the present embodiment.A vehicle VE of the present embodiment may include a first power supply 12, a second power supply 22, a first external sensor 18, a second external sensor 28, a first electronic control unit (ECU) 14, a second electronic control unit 24, and a converter 100.Referring to FIG. 1, the vehicle VE may include: a first power supply 12 that provides a DC voltage; a first external sensor 18 including a torque sensor and an angle sensor; a first electronic control unit 14 that receives a first voltage output from the first power supply 12, converts the first voltage output from the first power supply 12 into a first pulse having a constant frequency, outputs the first pulse to a first steering motor 16, and generates a voltage lower than the provided voltage to output it to the first external sensor 18; a second power supply 22 that provides a DC voltage; a second external sensor 28 including a torque sensor and an angle sensor; a second electronic control unit 24 that receives an output voltage from the second power supply 22, converts the voltage into a second pulse having a constant frequency, outputs the second pulse to a second steering motor 26, and generates a voltage lower than the supplied voltage to output it to the second external sensor 28; and a converter 100 for receiving power from another power supply when a failure occurs in either the first power supply 12 or the second power supply 22 and the power supply is cut off, and supplying the power to the first electronic control unit 14 or the second electronic control unit 24 to which the power supply is cut off.The first power supply 12 may include a battery and supply a DC voltage to the first electronic control unit 14.The first power supply 12 may include at least one of a DC voltage and an AC voltage.The first external sensor 18 may include a torque sensor that measures a torsion force acting on a rotating member such as the steering wheel SW of a vehicle, and an angle sensor that measures a position or a rotation angle of a rotating member such as the steering wheel SW.The first external sensor 18 may be connected to the first electronic control unit 14 and collect and relay information on the steering state and the environment of the vehicle to the first electronic control unit 14.The first electronic control unit 14 may be powered by the first power supply 12 and may power the first steering motor 16 and the first external sensor 18.That is, the first electronic control unit 14 may be supplied with a first output voltage from the first power supply 12, convert the first output voltage from the first power supply 12 into a first pulse having a certain frequency, output the first pulse to the first steering motor 16, and generate a voltage lower than the supplied voltage, and output the voltage lower than the supplied voltage to the first external sensor 18.The first electronic control unit 14 may electronically control the operation of the first steering motor 16 in response to the signal of the first external sensor 18.In this case, the first electronic control unit 14 may include a first voltage detector 211 that monitors the output power of the first power supply 12 to determine whether the first power supply 12 is abnormal.The first voltage detector 211 may monitor the voltage output from the first power supply 12 to detect whether the first power supply 12 is abnormal, and may relay the state information of the first power supply 12 to a first microcontroller (MCU) 213 or a second MCU 223.The second power supply 22 may include a battery and supply a DC voltage to the second electronic control unit 24.The second power supply ( 2) can contain at least one DC voltage or one AC voltage.The second external sensor 28 may include a torque sensor that measures a torsion force applied to a rotating member such as the steering wheel SW of a vehicle, and an angle sensor that measures a position or a rotation angle of a rotating member such as the steering wheel SW.The second external sensor 28 may be connected to the second electronic control unit 24 and collect and relay information on the steering state and the environment of the vehicle to the second electronic control unit 24.The second electronic control unit 24 may be powered by the second power supply 22 and may power the second steering motor 26 and the second external sensor 28.That is, the second electronic control unit 24 may receive a voltage output from the second power supply 22, convert the voltage output from the second power supply 22 into a second pulse having a certain frequency, output the second pulse to the second steering motor 26, and generate a voltage lower than the supplied voltage, and output the lowered voltage to the second external sensor 28.The second electronic control unit 24 may electronically control the operation of the second steering motor 26 in response to the signal of the second external sensor 28.In this case, the second electronic control unit 24 may include a second voltage detector 221 that monitors the power output from the second power supply 22 to determine whether the second power supply 22 is abnormal.The second voltage detector 221 may monitor the voltage output from the second power supply 22 to detect whether the second power supply 22 is abnormal, and may relay the state information of the second power supply 22 to the first MCU 213 or the second MCU 223.When a failure occurs in the first power supply 12 or the second control device 22 and the power supply is cut off, the converter 100 may receive power from another power supply and output power to the first electronic control unit 14 or the second electronic control unit 24 whose power supply is cut off.In this case, the first MCU 213 of the first electronic control unit 14 or the second MCU 223 of the second electronic control unit 24 may determine whether there is an abnormality in the first power supply 12 or the second power supply 22 based on the detection signals of the first voltage detector 211 and the second voltage detector 221, and control the converter 100.In this way, the vehicle of the present embodiment can control the converter 100 so that the two independent electronic control units can operate continuously by receiving power from another power supply if the power supply of one of the two independent electronic control units is cut off or a failure occurs in the power supply connected to one of the two independent electronic control units.The electric steering of the vehicle VE may be specifically understood to mean a system capable of changing the steering angle of the steering wheel based on the steering force (or rotational force) applied to the steering wheel by the driver.The electric steering system of the vehicle VE may be configured with a redundant structure that uses two independent external sensors and two independent electronic control units (ECUs) to control two independent steering motors, respectively. In this case, the steering motor can be configured as a single motor or with a double-winding structure in order to form a redundant structure. That is, various windings may be wound on a motor core and current flow may be controlled by each independent electronic control unit.In one aspect, the electric steering system of the present embodiment may include a first electronic control unit 14, a second electronic control unit 24, and a converter 100.Referring to FIGS. 2, 3 to 4, the electric steering system of the vehicle VE may include a first electronic control unit 14 that converts a first voltage output from a first power supply into a first constant frequency pulse, outputs the first pulse to a first steering motor 16, and outputs a voltage lower than the first voltage output from the first power supply to a first external sensor 18; a second electronic control unit 24 that converts a second voltage output from a second power supply into a second constant frequency pulse, outputs the second pulse to a second steering motor 26, and outputs a voltage lower than the second voltage output from the second power supply to a second external sensor 28 and converter 100. In the event of a failure of the first power supply 12 or the second power supply 22, the converter 100 may receive the power from another power supply and output a power supplied from another power supply of the first or second power supply in which the failure does not occur to one of the first electronic control units 14 or the second electronic control unit 24 whose power supply is interrupted by the first power supply or the second power supply.The first electronic control unit 14 may be supplied with the first voltage output from the first power supply 12, convert the supplied voltage into a first pulse having a certain frequency, output the first pulse to the first steering motor 16, and generate a voltage lower than the supplied voltage, and output the lowered voltage to the first external sensor 18.The first electronic control unit 14 may electronically control the operation of the first steering motor 16 in response to the signal of the first external sensor 18.The second electronic control unit 24 may receive the voltage output from the second power supply 22, convert the received voltage into a second pulse having a certain frequency, output the second pulses to the second steering motor 26, and generate a voltage lower than the supplied voltage, and output the lowered voltage to the second external sensor 28.The second electronic control unit 24 may electronically control the operation of the second steering motor 26 in response to the signal of the second external sensor 28.When a failure occurs in the first power supply 12 or the second power supply 22 and the power supply is cut off, the converter (converter unit) 100 may receive power from the other power supply and output the power from the other power supply to the first electronic control unit 14 or the second electronic control unit 24 whose power supply is cut off.In an embodiment, the converter 100 may include a first primary coil T 11 to which a first voltage is applied from a first power supply 12, and a first input node (first input unit) 216 having a first controller 215 connected to an output terminal of the first primary coil T 11 to control the current flow of the first primary coil T 11.In addition, the converter 100 may include a first output node (first output unit) 226 including a first secondary coil T 12 isolated from the first primary coil T 11 and generating and outputting a second voltage supplied to the second electronic control unit 24, a first diode D 1 connected to an output terminal of the first secondary coil T 12 and blocking the reverse current, and a first capacitor C 1 connected between an output terminal of the first diode D 1 and a ground terminal of the first secondary coil T 12 and maintaining the output voltage uniformly.Moreover, the first electronic control unit 14 may include a first MCU 213 that controls the output voltage by controlling the duty ratio of a first switch S 1 connected to the first primary coil T 11 or controls the output voltage by controlling the switching frequency.Moreover, the first electronic control unit 14 may include a first power converter 212 that receives the first output voltage from the first power supply 12, generates a voltage lower than the first output voltage from the first power supply 12, and supplies this voltage to the first MCU 213 and the first external sensor 18.Moreover, the first electronic control unit 14 may include a first inverter that receives the first voltage from the first power supply 12, converts the received voltage into a first pulse having a certain frequency, and supplies the first pulse to the first steering motor 16.The first MCU 213 may control the output voltage of the first secondary coil T 12 by controlling the duty ratio of the first switch S 1 connected to the first primary coil T 11 or may control the output voltage of the first secondary coil T 12 by controlling the switching frequency.For example, the first MCU 213 may control the switching period and the duty ratio by turning on and off the first switch S 1 using a PWM controller.The first power converter 212 may receive the first output voltage from the first power supply 12, generate a lower voltage than the first output voltage from the first power supply 12, and supply the lower voltage to the first MCU 213 and the first external sensor 18.The first inverter may receive the first voltage from the first power supply 12, convert the received voltage into a first constant frequency pulse, and supply the first pulse to the first steering motor 16.The converter 100 may include a first input node 216 and a first output node 226. In addition, in the event of a fault in the second control device 22 and an interruption of the power supply of the second electronic control unit 24, the second electronic control unit 24, the power supply of which is interrupted, can be supplied with power from the first control device 12.The first input node 216 may be provided in the first electronic control unit 14 and include a primary coil T 11 to which a first output voltage of the first power supply 12 is applied, and a first controller 215 connected to an output terminal of the first primary coil T 11 to control the current flow of the first primary coil T 11.Moreover, the first output node 226 may be configured in the second electronic control unit 24, and may include a first secondary coil T 12 isolated from the first primary coil T 11 and generating and outputting a second voltage supplied to the second electronic control unit 24, a first diode D 1 located at an output terminal of the first secondary coil T 12 and blocking the reverse current, and a first capacitor C 1 located between an output terminal of the first diode D 1 and a ground terminal of the first secondary coil T 12 and maintaining the output voltage uniformly.The first controller 215 may include a first switch S 1 that is turned on to flow current in the first primary coil T 11 and turned off to flow current in the first secondary coil T 12.The first switch S 1 may include a drain terminal (D), a source terminal (S), and a gate terminal (G), and may be formed as a field effect transistor (MOSFET) whose gate terminal is connected to the first MCU 213, whose source terminal is connected to the output terminal of the first primary coil T 11, and whose drain terminal is connected to the ground.The first diode D 1 may be located at the output terminal of the first secondary coil T 12 and may block the reverse current.Moreover, the first capacitor C 1 may be disposed between the output terminal of the first diode D 1 and the ground terminal of the first secondary coil T 12 and may uniformly maintain the output voltage.Moreover, the first output node 226 may include a third diode D 3 that is disposed between the output terminal of the first diode D 1 and the second power converter 222 or the second inverter 224 and prevents reverse flow of the output current to the second power converter 222 or the second inverter 224.The third diode D 3 may be disposed between the output terminal of the first diode D 1 and the second power converter 222 or the second inverter 224 and may prevent a reverse flow of the output current to the second power converter 222 or the second inverter 224.For example, when the first switch S 1 of the converter 100 is turned on, the input voltage of the first power supply 12 may be applied to the first primary coil T 11 and current may flow through the first primary coil T 11, thereby storing electric energy in the coil. In this case, no current flow through the first secondary coil T 12 may take place.Then, when the first switch S 1 is turned off, the current flowing through the first primary coil T 11 may be interrupted, and the magnetic flux decreases, thereby generating an induced voltage in the first secondary coil T 12.In this case, the induced voltage may be transmitted to the output terminal via the first diode D 1 and may be uniformly maintained by the second capacitor C 2 to be supplied to the first power converter 212 or the first inverter 214.Here, as shown in FIG. 3, the converter 100 may be configured as a low power converter that decreases the input voltage and provides the decreased input voltage as an output voltage, so that the second power converter 222 receives the minimum power required for powering the second MCU 223 and the second external sensor 28.Such a low power converter may be miniaturized and light weight, which lowers cost and increases efficiency.For example, when a fault occurs in the second power supply 22 and the power supply is cut off, the first MCU 213 may control the first switch such that the converter 100 generates a voltage lower than the first voltage output from the first power supply 12 and outputs the lowered voltage to the second power converter 222, and the second power converter 222 may receive the voltage output from the converter 100 and supply it to the second MCU 223 and the second external sensor 28.In addition, when the second power converter 222 receives the voltage output from the converter 100 and supplies it to the second MCU 223 and the second external sensor 28, the second MCU 223 may collect data from the second external sensor 28 and transmit it to the first MCU 213.In this way, in the event of an interruption of the power supply of one of the two independent sensors or in the event of a failure of the power supply connected to one of the two independent sensors, current can be supplied from another power supply, so that the two independent sensors can continue to operate, whereby accurate data acquisition by the two independent sensors is made possible, and even in the event of a malfunction of one sensor, the failed sensor can be replaced by the other sensor.As illustrated in FIG. 4, the converter 100 may be configured as a high-power converter that increases the input voltage and provides the increased input voltage as an output voltage, so that the second power converter 222 may supply power to the second MCU 223 and the second external sensor 28, and the second inverter 224 may receive power and supply power to the second steering motor 26.Such a high power converter can provide a high output power and a high efficiency, thereby improving stability.For example, when a fault occurs in the second power supply 22 and the power supply is cut off, the first MCU 213 may control the first switch such that the converter 100 generates a voltage corresponding to the first output voltage of the first power supply 12 and outputs the generated voltage to the second power converter 222 and the second inverter 224. The second power converter 222 may receive the voltage output from the converter 100 and supply it to the second MCU 223 and the second external sensor 28. The second inverter 224 may receive the voltage output from the converter 100, convert it into a second pulse having a constant frequency, and supply the second pulse to the second steering motor 26.In this way, in one embodiment, even if the power supply to the second electronic control unit 24 is interrupted or the second power supply 22 fails, the power can be supplied from the first power supply 12 to continuously operate two independent steering motors via two independent electronic control units.In another aspect, the electric steering system of the present embodiment may include a first electronic control unit 14, a second electronic control unit 24, and a converter 100.Referring to FIGS. 5, 6 to 7, the electric steering system of the vehicle VE may include a first electronic control unit 14 that receives an output voltage from a first power supply 12, converts the received voltage into a first constant frequency pulse, outputs the first pulse to a first steering motor 16 and generates a voltage lower than the supplied voltage, and outputs the lowered voltage to a first external sensor 18; a second electronic control unit 24 that receives a voltage output from a second power supply 22, converts the received voltage into a second constant frequency pulse, outputs the second pulse to a second steering motor 26 and generates a voltage lower than the supplied voltage, and outputs the lowered voltage to a second external sensor 28, and a converter 100. In the event of a failure of the first power supply 12 or the second control device 22 and a disconnection of the power supply, the converter 100 may acquire the power from another power supply and output the power to the first electronic control unit 14 or the second electronic control unit 24, the power supply of which is disconnected.The first electronic control unit 14 may be supplied with the first voltage output from the first power supply 12, convert the received voltage into a first pulse having a certain frequency, output the first pulse to the first steering motor 16, and generate a voltage lower than the supplied voltage, and output the lowered voltage to the first external sensor 18.The first electronic control unit 14 may electronically control the operation of the first steering motor 16 in response to the signal of the first external sensor 18.The second electronic control unit 24 may receive the voltage output from the second power supply 22, convert the voltage into a second pulse having a certain frequency, output the second pulse to the second steering motor 26, and generate a voltage lower than the supplied voltage to output it to the second external sensor 28.The second electronic control unit 24 may electronically control the operation of the second steering motor 26 in response to the signal of the second external sensor 28.In another embodiment, the converter 100 may include a second input node 228 having a second primary coil T 21 to which the voltage output from the second power supply 22 is applied, and a second controller 225 connected to the output terminal of the second primary coil T 21 and controlling the current flow of the second primary coil T 21, and a second output node 218 including a second secondary coil T 22 isolated from the second primary coil T 21 and outputting a voltage supplied to the first electronic control unit 14, a second diode D 2 disposed at the output terminal of the second secondary coil T 22 and blocking the reverse current, and a second capacitor C 2 disposed between the output terminal of the second diode D 2 and the ground terminal of the second secondary coil T 22 and maintaining the output voltage uniformly.In addition, the second electronic control unit 24 may include a second MCU 223 that controls the output voltage by controlling the duty ratio of a second switch S 2 connected to the secondary coil T 21 or the output voltage by controlling the switching frequency; a second power converter 222 that receives the output voltage from the second power 22 and generates a voltage lower than the output voltage from the second power 22 and supplies the voltage lower than the output voltage from the second power 22 and the second external sensor 28; and a second inverter that receives the output voltage from the second power 22, converts it into a second pulse having a certain frequency, and supplies the second pulse to the second steering motor 26.The second MCU 223 may control the output voltage of the second secondary coil T 22 by controlling the duty ratio of the second switch S 2 connected to the second primary coil T 21, or may control the output voltage of the second secondary coil T 22 by controlling the switching frequency.For example, the second MCU 223 may control the switching period and the duty ratio by turning on and off the second switch S 2 using a PWM controller.The second power converter 222 may be supplied with the voltage output from the second power supply 22, generate a voltage lower than the voltage output from the second power supply 22, and supply the voltage lower to the second MCU 223 and the second external sensor 28.The second inverter may receive the voltage output from the second power supply 22, convert it into a second pulse having a certain frequency, and output the second pulse to the second steering motor 26.The converter 100 may include a second input node 228 and a second output node 218. When a failure occurs in the first power supply 12 and the power supply of the first electronic control unit 14 is cut off, the power may be supplied from the second power supply 22, and the power may be output to the first electronic control unit 14 whose power supply is cut off.The second input node 228 may be provided in the second electronic control unit 24 and include a second primary coil T 21 to which the voltage output from the second power supply 22 is applied, and a second controller 225 connected to the output terminal of the second primary coil T 21 to control the current flow of the second primary coil T 21.Moreover, the second output node 218 may be configured in the first electronic control unit 14 and include a second secondary coil T 22 that is insulated from the second primary coil T 21 and generates and outputs a voltage supplied to the first electronic control unit 14, a second diode D 2 that is located at the output terminal of the second secondary coil T 22 and blocks the reverse current, and a second capacitor C 2 that is located between the output terminal of the second diode D 2 and the ground terminal of the second secondary coil T 22 and uniformly maintains the output voltage.The second controller 225 may include a second switch S 2 that is turned on to flow current in the second primary coil T 21 and turned off to flow current in the second secondary coil T 22.The second switch S 2 may include a drain terminal (D), a source terminal (S), and a gate terminal (G), and may be formed of a field effect transistor (MOSFET) whose gate terminal is connected to the second MCU 223, whose source terminal is connected to the output terminal of the second primary coil T 21, and whose drain terminal is connected to the ground.The second diode D 2 may be located at the output terminal of the second secondary coil T 22, and may block the reverse current.Moreover, the second capacitor C 2 may be disposed between the output terminal of the second diode D 2 and the ground terminal of the second secondary coil T 22, and may uniformly maintain the output voltage.Moreover, the second output node 218 may be disposed between the output terminal of the second diode D 2 and the first power converter 212 or the first inverter 214, and may include a fourth diode D 4 for preventing reverse flow of the output current to the first power converter 212 or the first inverter 214.The fourth diode D 4 may be disposed between the output terminal of the second diode D 2 and the first power converter 212 or the first inverter 214, and may prevent the reverse flow of the output current to the first power converter 212 or the first inverter 214.For example, when the second switch S 2 of the converter 100 is turned on, the input voltage of the second power supply 22 may be applied to the second primary coil T 21, and current may flow through the second primary coil T 21, thereby storing electric energy in an inductance. In this case, no current flow through the second secondary coil T 22 may take place.When the second switch S 2 is turned off, the current flow in the second primary coil T 21 may be interrupted and the magnetic flux may decrease, so that an induced voltage may be generated in the second secondary coil T 22.In this case, the induced voltage may be transmitted to the output terminal via the second diode D 2 and may be uniformly maintained by the second capacitor C 2 to be supplied to the first power converter 212 or the first inverter 214.Here, as illustrated in FIG. 6, the converter 100 may be configured as a low power converter that decreases the input voltage and provides the decreased input voltage as an output voltage, so that the first power converter 212 may absorb the minimum power required for powering the first MCU 213 and the first external sensor 18.Such low power converters may be miniaturized and light weight, which lowers costs and increases efficiency.For example, when a fault occurs in the first power supply 12 and the power supply is cut off, the second MCU 223 may control the second switch so that the converter 100 generates a voltage lower than the voltage output from the second power supply 22 and outputs it to the first power converter 212. The first power converter 212 may receive the voltage output from the converter 100 to supply the first MCU 213 and the first external sensor 18.In addition, when the first power converter 212 receives the voltage output from the converter 100 and supplies it to the first MCU 213 and the first external sensor 18, the first MCU 213 may acquire data of the first external sensor 18 and transmit it to the second MCU 223.Here, the first MCU and the second MCU may collect data of the first external sensor or the second external sensor and exchange the collected data with each other.In this way, in the event of an interruption of the power supply for one of the two independent sensors or in the event of a failure of the power supply connected to one of the two independent sensors, the power can be supplied from another power supply, so that the two independent sensors can operate continuously, whereby the detection of precise data by the two independent sensors is made possible. In addition, in the event of a malfunction of one sensor, the failed sensor can be replaced by another sensor.As illustrated in FIG. 7, the converter 100 may be configured as a high-power converter that increases the input voltage and provides the increased input voltage as an output voltage to have the first power converter 212 supply power to the first MCU 213 and the first external sensor 18. The first inverter 214 may receive power to power the first steering motor 16.Such a high power converter can provide a high output power and a high efficiency and increase stability.For example, when a fault occurs in the first power supply 12 and the power supply is cut off, the second MCU 223 may control the second switch so that the converter 100 generates a voltage corresponding to the voltage output from the second power supply 22 and outputs it to the first power converter 212 and the first inverter 214. The first power converter 212 may receive the voltage output from the converter 100 to supply the first MCU 213 and the first external sensor 18. The first inverter 214 may receive the voltage output from the converter 100, convert the voltage output from the converter 100 into a first pulse having a constant frequency, and supply the first pulse to the first steering motor 16.In another embodiment, upon interruption of the power supply to the first electronic control unit 14 or upon failure of the first power supply 12, power may be supplied from the second power supply 22 to continuously operate two independent steering motors via two independent electronic control units.In another embodiment, as shown in FIG. 8, the converter 100 may include a first input node 216, a first output node 226, a second input node 228, and a second output node 218.That is, the converter 100 may include a primary coil T 11 to which a first voltage is applied from the first power supply 12, and a first input node 216 having a first controller 215 connected to the output terminal of the first primary coil T 11 to control the current flow of the first primary coil T 11.In addition, the converter 100 may include a first output node 226 having a first secondary coil T 12 isolated from the first primary coil T 11 and generating and outputting a second voltage supplied to the second electronic control unit 24, a first diode D 1 located at the output terminal of the first secondary coil T 12 and blocking the reverse current, and a first capacitor C 1 located between the output terminal of the first diode D 1 and the ground terminal of the first secondary coil T 12 and maintaining a uniform output voltage.Moreover, the converter 100 may include a second primary coil T 21 to which a voltage output from a second power supply 22 is applied, and a second input node 228 having a second controller 225 connected to an output terminal of the second primary coil T 21 to control the current flow of the second primary coil T 21.In addition, the converter 100 may include a second output node 218 having a second secondary coil T 22 isolated from the second primary coil T 21 and outputting a voltage supplied to the first electronic control unit 14, a second diode D 2 located at the output terminal of the second secondary coil T 22 and blocking the reverse current, and a second capacitor C 2 located between the output terminal of the second diode D 2 and the ground terminal of the second secondary coil T 22 and maintaining a uniform output voltage.Here, the first input node 216 and the first output node 226 may be formed by low power converters, and the second input node 228 and the second output node 218 may be formed by high power converters. Alternatively, the first input node 216 and the first output node 226 may be formed by high power converters and the second input node 228 and the second output node 218 may be formed by low power converters.Alternatively, the first input node 216, the first output node 226, the second input node 228, and the second output node 218 may also be formed by low power converters or high power converters.In another aspect, the control method of the electric power steering system of the present embodiment may include a first step of energization and a second step of energization. The first stage of the power supply is the provision of the first power. And the second stage of the power supply is the provision of the second power.Referring to FIG. 9, a control method of an electric power steering system of a vehicle VE may include a first step of power supply in which a first electronic control unit 14 receives a voltage output from a first power supply 12, converts it into a first constant frequency pulse, outputs the first pulse to a first steering motor 16, generates a voltage lower than the supplied voltage, and outputs the lowered voltage to a first external sensor 18, and a second electronic control unit 24 receives an output voltage from a second power supply 22, converts it into a second constant frequency pulse, outputs the second pulse to a second steering motor 26, generates a voltage lower than the supplied voltage, and outputs the lowered voltage to a second external sensor 28 (S 1010).Moreover, the control method of the electric power steering system of the vehicle VE may include a second step of power supply S 1020 in which the converter 100 receives power from another power supply and outputs the power to the first electronic control unit 14 or the second electronic control unit 24, the power supply of which is cut off when a failure occurs in the first power supply 12 or the second power supply 22 (S 1020).In the first step of energization (S 1010), the first electronic control unit 14 may receive the first voltage output from the first power supply 12, convert the received voltage into a first pulse having a certain frequency, and output the first pulse to the first steering motor 16. Moreover, in the first step of energization (S 1010), a voltage lower than the supplied voltage may be generated and output to the first external sensor 18, and the second electronic control unit 24 may receive the voltage output from the second power supply 22, convert the supplied voltage into a second pulse having a certain frequency, output the second pulse to the second steering motor 26, and generate a voltage lower than the supplied voltage to output it to the second external sensor 28.Moreover, in step S 1020 of the second power supply, when either the first power supply 12 or the second power supply 22 fails and the power supply is cut off, the converter 100 may receive the power from another power supply to output it to the first electronic control unit 14 or the second electronic control unit 24 whose power supply is cut off.In this case, the second power supply step (S 1020) may further include a step in which the first MCU 213 controls the first switch to cause the converter 100 to generate a voltage lower than the first voltage output from the first power supply 12 and output the lowered voltage to the second power converter 222 when a failure occurs in the second power supply 22 and the power supply is cut off.Moreover, the second step of energization (S1020) may include a step in which the second power converter 222 receives the voltage output from the converter 100 and supplies the received voltage to the second MCU 223 and the second external sensor 28.That is, in the second step of power supply (S 102), when a failure occurs in the second power supply 22 and the power supply is interrupted or stopped, the converter 100 may generate a voltage lower than the first voltage output from the first power supply 12 and output the lowered voltage to the second power converter 222, and the first MCU 213 controls the first switch so that the second power converter 222 receives the voltage output from the converter 100 and supplies the received voltage to the second MCU 223 and the second external sensor 28.In this case, the converter 100 may be configured as a low power converter that decreases the input voltage and provides the decreased voltage as the output voltage, so that the second power converter 222 may receive the minimum power required for supplying power to the second MCU 223 and the second external sensor 28.The low power converters may be miniaturized and light weight, which lowers costs and increases efficiency.Alternatively, the second power supply step (S 1020) may also include a step in which the first MCU 213 controls the first switch such that the converter 100 generates a voltage corresponding to the first voltage output from the first power supply 12 and outputs the generated voltage to the second power converter 222 and the second inverter 224 when the second power supply 22 fails and the power supply is cut off.Moreover, the second step of power supply (S1020) may include another step in which the second power converter 222 receives the voltage output from the converter 100 and supplies the received voltage to the second MCU 223 and the second external sensor 28.Moreover, the second step of energization (S 102) may include a step in which the second inverter 224 receives the voltage output from the converter 100, converts the received voltage into a second pulse having a certain frequency, and supplies the second pulse to the second steering motor 26.That is, when a fault occurs in the second power supply 22 and the power supply is cut off in the second stage of the power supply (S 102), the first MCU 213 may control the first switch such that the converter 100 generates a voltage corresponding to the first voltage output from the first power supply 12 and outputs the generated voltage to the second power converter 222 and the second inverter 224. Moreover, the second step of energization (S 1020) may be configured such that the second power converter 222 receives the voltage output from the converter 100 and supplies it to the second MCU 223 and the second external sensor 28. The second inverter 224 may receive the voltage output from the converter 100, convert the received voltage into a second pulse having a certain frequency, and supply the second pulse to the second steering motor 26.In this case, the converter 100 may be configured as a high-power converter capable of increasing the input voltage and providing the increased input voltage as an output voltage, so that the second power converter 222 may supply power to the second MCU 223 and the second external sensor 28, and the second inverter 224 may receive power to supply power to the second steering motor 26)The high-power converter may provide high output power and high efficiency and increase stability.Alternatively, the second power supply step (S1020) may include a step in which the second MCU 223 controls the second switch such that the converter 100 generates a voltage lower than the voltage output from the second power supply 22 and outputs the lowered voltage to the first power converter 212 when a failure occurs in the first power supply 12 and the power supply is cut off; and a step in which the first power converter 212 receives the voltage output from the converter 100 and supplies the received voltage to the first MCU 213 and the first external sensor 18.That is, in the second step of power supply (S1020), when a failure occurs in the first power supply 12 and the power supply is cut off, the power converter 100 may generate a voltage lower than the voltage output from the second power supply 22 and output the lowered voltage to the first power converter 212, and the second MCU 223 may control the second switch such that the first power converter 212 receives the voltage output from the power converter 100 and outputs it to the first MCU 213 and the first external sensor 18.Here, the converter 100 may be configured as a low power converter that decreases the input voltage and provides the decreased voltage as the output voltage, so that the first power converter 212 may absorb the minimum power required for supplying power to the first MCU 213 and the first external sensor 18.Such low power converters may be miniaturized and lightweight, which lowers costs and increases efficiency.Alternatively, the second power supply step (S1020) may also include a step in which the second MCU 223 controls the second switch so that the converter 100 generates a voltage corresponding to the voltage output from the second power supply 22, and outputs it to the first power converter 212 and the first inverter 214 when the first power supply 12 fails and the power supply is cut off.Moreover, the second step of energizing (S1020) may also include a step in which the first power converter 212 receives the voltage output from the converter 100 and supplies the received voltage to the first MCU 213 and the first external sensor 18.Moreover, the second step of energization (S 102) may include a step in which the first inverter 214 receives the voltage output from the converter 100, converts the received voltage into a first pulse having a certain frequency, and supplies the first pulse to the first steering motor 16.That is, in the second step of power supply (S1020), when a failure occurs in the first power supply 12 and the power supply is cut off, the second MCU 223 may control the second switch such that the converter 100 generates a voltage corresponding to the voltage output from the second power supply 22 and outputs it to the first power converter 212 and the first inverter 214, and the first power converter 212 receives the voltage output from the converter 100 and supplies it to the first MCU 213 and the first external sensor 18, and the first inverter 214 receives the voltage output from the converter 100 and converts the received voltage into a first pulse having a constant frequency and supplies the first pulse to the first steering motor 16.Here, the converter 100 may be configured as a high-power converter capable of increasing the input voltage and providing the increased input voltage as an output voltage, so that the first power converter 212 may supply power to the first MCU 213 and the first external sensor 18 and the first inverter 214 receives power to supply the first steering motor 16.Such a high power converter can provide a high output power and a high efficiency and increase stability.In this way, in the present embodiment, in the event of power supply of one of the two independent electronic control units being interrupted or power supply connected to one of the two independent electronic control units being broken, power can be supplied from another power supply, so that the two independent electronic control units can operate continuously.The above description is provided to enable a person skilled in the art to make and use the technical spirit of the present disclosure, and is provided in connection with a particular application and its requirements. Various modifications, additions and substitutions to the described embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. The above description and the accompanying drawings provide an example of the technical spirit of the present disclosure only for illustrative purposes. That is, the disclosed embodiments are intended to illustrate the scope of the technical spirit of the present disclosure. Thus, the scope of the present disclosure is not limited to the illustrated embodiments, but must conform to the broadest scope still consistent with the claims.The scope of the present disclosure should be construed by the following claims, and all technical ideas within the range corresponding to these claims should be construed as being included in the right-handed range of the present disclosure.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedKR 10-2024-090935

[0001]

Claims

An electric power steering system comprising: a first electronic control unit (14) configured to convert a first voltage output from a first power supply (12) into a first pulse having a constant frequency, output the first pulse to a first steering motor (16), and output a voltage lower than the first voltage output from the first power supply (12) to a first external sensor (18); a second electronic control unit (24) configured to convert a second voltage output from a second power supply (22) into a second pulse having a constant frequency, output the second pulse to a second steering motor (26), and output a voltage lower than the second voltage output from the second power supply (22) to a second external sensor (28); and a converter (100) configured to, when a failure occurs in one of the first power supply (12) and the second power supply (22), supply a power supplied from another of the first power supply (12) and the second power supply (22) in which the failure does not occur to one of the first electronic control unit (14) and the second electronic control unit (24) in which the power supply from the one of the first power supply (12) and the second power supply (22) is cut off.The electric power steering system according to claim 1, wherein the converter (100) comprises: a first input node (216) having a first primary coil (T11) to which the first voltage output from the first power supply (12) is applied, and a first controller (215) connected to an output terminal of the first primary coil (T11) to control a current flow of the first primary coil (T11); and a first output node (226) including a first secondary coil (T12) isolated from the first primary coil (T11) and configured to output the second voltage supplied to the second electronic control unit (24), a first diode (D1) connected to an output terminal of the first secondary coil (T12), and a first capacitor (C1) connected between an output terminal of the first diode (D1) and a ground terminal of the first secondary coil (T12).The electric power steering system according to claim 2, wherein the first controller (215) includes a first switch (S1) configured to be turned on to allow current to flow through the first primary coil (T11), and turned off to allow current to flow through the first secondary coil (T12).The electric power steering system according to claim 3, wherein the first electronic control unit (14) includes a first microcontroller (MCU) (213) configured to control an output voltage by controlling a duty ratio of the first switch (S1) or by controlling a switching frequency.The electric power steering system according to claim 4, wherein the first electronic control unit (14) comprises: a first power converter (212) configured to be supplied with the first voltage output from the first power supply (12), generate the voltage lower than the first voltage output from the first power supply (12), and supply the voltage lower than the first voltage output from the first power supply (12) to the first MCU (213) and the first external sensor (18); and a first inverter (214) configured to be supplied with the first voltage output from the first power supply (12), convert the first voltage output from the first power supply (12) into the first pulse having the constant frequency, and supply the first pulse to the first steering motor (16).The electric power steering system according to claim 5, wherein the converter (100) comprises: a second input node (228) having a second primary coil (T21) to which the second voltage output from the second power supply (22) is applied, and a second controller (225) connected to an output terminal of the second primary coil (T21) to control a current flow of the second primary coil (T21); and a second output node (218) having a second secondary coil (T22) isolated from the second primary coil (T21) and configured to output the first voltage supplied to the first electronic control unit (14), a second diode (D2) connected to an output terminal of the second secondary coil (T22), and a second capacitor (C2) connected between an output terminal of the second diode (D2) and a ground terminal of the second secondary coil (T22).The electric power steering system according to claim 6, wherein the second control device (225) includes a second switch (S2) configured to be turned on to allow current to flow through the second primary coil (T21) and turned off to allow current to flow through the second secondary coil (T22).The electric power steering system according to claim 7, wherein the second electronic control unit (24) includes a second MCU (223) configured to control an output voltage by controlling a duty ratio of the second switch (S2) or by controlling a switching frequency.The electric power steering system according to claim 8, wherein the second electronic control unit (24) comprises: a second power converter (222) configured to be supplied with the second voltage output from the second power supply (22), generate the voltage lower than the second voltage output from the second power supply (22), and supply the voltage lower than the second voltage output from the second power supply (22) to the second MCU (223) and the second external sensor (28); and a second inverter (224) configured to be supplied with the second voltage output from the second power supply (22), convert the second voltage output from the second power supply (22) into a pulse having a constant frequency, and supply the pulse to the second steering motor (26).The electric power steering system according to claim 9, wherein: the first MCU (213) is configured to control the first switch (S1) such that the converter (100) outputs the voltage lower than the first voltage output from the first power supply (12) to the second power converter (222) in a case where a failure occurs in the second power supply (22), and the second power converter (222) is configured to supply a voltage supplied from the converter (100) to the second MCU (223) and the second external sensor (28) in the case where the failure occurs in the second power supply (22).The electric power steering system according to claim 9 or 10, wherein: the first MCU (213) is configured to control, in a case where a failure occurs in the second power supply (22), the first switch (S1) such that the converter (100) outputs a voltage equal to the first voltage output from the first power supply (12) to the second power converter (222) and the second inverter (224), the second power converter (222) is configured to, in the case where the failure occurs in the second power supply (22), supply a voltage supplied from the converter (100) to the second MCU (223) and the second external sensor (28), and the second inverter (224) is configured to, in the case where the failure occurs in the second power supply (22), converting the voltage supplied from the converter (100) into the constant frequency pulse and supplying the pulse to the second steering motor (26).The electric power steering system according to any one of claims 9 to 11, wherein: the second MCU (223) is configured to control the second switch (S2) in a case where a failure occurs in the first power supply (12) such that the converter (100) outputs the voltage lower than the second voltage output from the second power supply (22) to the first power converter (212), and the first power converter (212) is configured to supply the voltage output from the converter (100) to the first MCU (213) and the first external sensor (18) in the case where the failure occurs in the first power supply (12).The electric power steering system according to claim 12, wherein the first MCU (213) and the second MCU (223) are configured to collect and share data from the first external sensor (18) and / or the second external sensor (28).The electric power steering system according to any one of claims 9 to 13, wherein: the second MCU (223) is configured to control the second switch (S2) in a case where a failure occurs in the first power supply (12) such that the converter (100) outputs a voltage equal to the second voltage output from the second power supply (22) to the first power converter (212) and the first inverter (214), the first power converter (212) is configured to supply the voltage output from the converter (100) to the first MCU (213) and the first external sensor (18) in the case where the failure occurs in the first power supply (12), converting the voltage output from the converter (100) into a pulse having a constant frequency and supplying the pulse to the first steering motor (16).A method of controlling an electric power steering system, the method comprising: by a first electronic control unit (14), converting a first voltage output from a first power supply (12) into a first constant frequency pulse, outputting the first pulse to a first steering motor (16), and outputting a voltage lower than the first voltage output from the first power supply (12) to a first external sensor (18); by a second electronic control unit (24), converting a second voltage output from a second power supply (22) into a second constant frequency pulse, outputting the second pulse to a second steering motor (26), and outputting a voltage lower than the second voltage output from the second power supply (22) to a second external sensor (28); and by a converter (100), when a fault occurs in one of the first power supply (12) and the second power supply (22), supplying one of another of the first power supply (12) and the second power supply (22) in which the fault does not occur, a power to one of the first electronic control unit (14) and the second electronic control unit (24) in which the power supply of the one of the first power supply (12) and the second power supply (22) is interrupted.The method of claim 15, wherein supplying the power to the one of the first electronic control unit (14) or the second electronic control unit (24) upon occurrence of a fault in the second power supply (22) comprises: by a first microcontroller (MCU) (213), controlling a first switch (S1) such that the converter (100) outputs the voltage lower than the first voltage output from the first power supply (12) to a second power converter (222); and by a second power converter (222), supplying the voltage output from the converter (100) to a second MCU (223) and the second external sensor (28).The method according to claim 15 or 16, wherein supplying the power to the one of the first electronic control unit (14) and the second electronic control unit (24) upon occurrence of a fault in the second power supply (12) comprises: by a second MCU (223), controlling a second switch (S2) such that the converter (100) outputs a voltage lower than the second voltage output from the second power supply (22) to a first power converter (212); and by the first power converter (212), supplying the voltage output from the converter (100) to a first MCU (213) and the first external sensor (18).A vehicle comprising: a first power supply (12) configured to supply a first DC voltage (DC); a first torque sensor and a first angle sensor; a first electronic control unit (14) configured to convert the first DC voltage output from the first power supply (12) into a first pulse having a constant frequency, output the first pulse to a first steering motor (16), and output a voltage lower than the first DC voltage output from the first power supply (12) to the first torque sensor and the first angle sensor; a second power supply (22) configured to supply a second DC voltage; a second torque sensor and a second angle sensor; a second electronic control unit (24) configured to convert the second DC voltage output from the second power supply (22) into a second pulse having a constant frequency, output the second pulse to a second steering motor (26), and output a voltage lower than the second DC voltage output from the second power supply (22) to the second torque sensor and the second angle sensor; and a converter (100) configured to, when a failure occurs in one of the first power supply (12) and the second power supply (22), supply a power supplied from another of the first power supply (12) and the second power supply (22) in which the failure does not occur to one of the first electronic control unit (14) and the second electronic control unit (24) in which the power supply from the one of the first power supply (12) and the second power supply (22) is cut off.The vehicle of claim 18, wherein the converter (100) comprises: a first input node (216) including a first primary coil (T11) to which the first DC voltage output from the first power supply (12) is applied; and a first controller (215) connected to an output terminal of the first primary coil (T11) to control a current flow of the first primary coil (T11); and a first output node (226) comprising a first secondary coil (T12) isolated from the first primary coil (T11) and configured to output the second direct current voltage supplied to the second electronic control unit (24), a first diode (D1) connected to an output terminal of the first secondary coil (T12), and a first capacitor (C1) connected between an output terminal of the first diode (D1) and a ground terminal of the first secondary coil (T12).The vehicle according to claim 18 or 19, wherein the converter (100) comprises: a second input node (228) including a second primary coil (T21) to which the second DC voltage output from the second power supply (22) is applied, and a second controller (225) connected to an output terminal of the second primary coil (T21) to control a current flow of the second primary coil (T21); and a second output node (218) having a second secondary coil (T22) isolated from the second primary coil (T21) and configured to output the first voltage supplied to the first electronic control unit (14), a second diode (D2) connected to an output terminal of the second secondary coil (T22), and a second capacitor (C2) connected between an output terminal of the second diode (D2) and a ground terminal of the second secondary coil (T22).

Images