Patent Publication Number: US-2022239111-A1

Title: On-board charger system with integrated auxiliary power supply

Description:
FIELD 
     Embodiments described herein relate to battery charging systems and, more particularly, relate to a charging system on-board a vehicle for charging a battery included in the vehicle. The charging system charges the battery from a power supply and provides an auxiliary power supply using power from the power supply or the battery. 
     SUMMARY 
     Typical power supply systems for an electric vehicle include a charging module for charging a primary battery of the vehicle from an external power source and a separate power supply module for generating an auxiliary power supply voltage, wherein the auxiliary power supply voltage is different than the primary battery voltage and may be used to power accessories of the vehicle. These separate modules increase the footprint and cost of the power supply system. 
     Accordingly, embodiments described herein provide an on-board charging system with an integrated auxiliary power supply and methods of operating the same. 
     For example, one embodiment provides a charger including a charging interface and a converter coupled to the charging interface. The converter includes a first plurality of switching transistors coupled to the charging interface and a transformer including a primary winding, a secondary winding, and an auxiliary winding. The primary winding is coupled to the first plurality of switching transistors. A second plurality of switching transistors is coupled between the secondary winding and a battery interface. An auxiliary system interface is coupled to the auxiliary winding. A controller is configured to control the first plurality of switching transistors and the second plurality of switching transistors to generate a first signal at the battery interface and a second signal at the auxiliary system interface. 
     Another embodiment provides a vehicle including a charging interface and a converter coupled to the charging interface. The converter includes a first plurality of switching transistors coupled to the charging interface and a transformer including a primary winding, a secondary winding, and an auxiliary winding. The primary winding is coupled to the first plurality of switching transistors. A second plurality of switching transistors is coupled between the secondary winding and a battery interface. An auxiliary system interface is coupled to the auxiliary winding. A battery is coupled to the battery interface. An inverter is coupled to the battery. A motor is coupled to the inverter. A controller is configured to control the first plurality of switching transistors and the second plurality of switching transistors to generate a first signal at the battery interface and a second signal at the auxiliary system interface. 
     Yet another embodiment provides a method including controlling, with a controller, a first plurality of switching transistors coupled to a primary winding of a transformer and a second plurality of switching transistors coupled between a secondary winding of the transformer and a battery interface to generate a first signal at the battery interface and a second signal at an auxiliary system interface coupled to an auxiliary winding of the transformer. 
     Other features and aspects will become apparent by consideration of the following detailed description and accompanying drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a power supply system according to one embodiment. 
         FIG. 2  is a circuit diagram of one embodiment of a charger included in the power supply system of  FIG. 1  for charging a battery and providing an auxiliary power supply. 
         FIG. 3  is a circuit diagram of another embodiment of a charger included in the power supply system of  FIG. 1  for charging a battery and providing an auxiliary power supply. 
     
    
    
     DETAILED DESCRIPTION 
     One or more embodiments are described in the following description and illustrated in the accompanying drawings. These embodiments are not limited to the specific details provided herein and may be modified in various ways. Furthermore, other embodiments may exist that are not described herein. Also, the functionality described herein as being performed by one component may be performed by multiple components in a distributed manner. Likewise, functionality described herein as being performed by multiple components may be consolidated and performed by a single component. Similarly, a component described as performing particular functionality may also perform additional functionality not described herein. For example, a device or structure that is “configured” in a certain way is configured in at least that way but may also be configured in ways that are not listed. Furthermore, some embodiments described herein may include one or more electronic processors configured to perform the described functionality (or portions thereof) by executing instructions stored in non-transitory, computer-readable medium. Similarly, embodiments described herein may be implemented as non-transitory, computer-readable medium storing instructions executable by one or more electronic processors to perform the described functionality. As used in the present application, “non-transitory, computer-readable medium” comprises all computer-readable media but does not consist of a transitory, propagating signal. Accordingly, non-transitory computer-readable medium may include, for example, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a RAM (Random Access Memory), register memory, a processor cache, or any combination thereof. 
     In addition, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. For example, the use of “including,” “containing,” “comprising,” “having,” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “connected” and “coupled” are used broadly and encompass both direct and indirect connecting and coupling. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings and can include electrical connections or couplings, whether direct or indirect. In addition, electronic communications and notifications may be performed using wired connections, wireless connections, or a combination thereof and may be transmitted directly or through one or more intermediary devices over various types of networks, communication channels, and connections. Moreover, relational terms such as first and second, top and bottom, and the like may be used herein solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. 
       FIG. 1  is a block diagram of a power supply system  100  according to one embodiment. The power supply system  100  includes a charger  105  for charging a battery  110  using power from a power source  115 . The battery  110  provides power to a drive unit  120 . In some embodiments, the drive unit  120  includes an inverter  125  for generating an alternating current power signal for driving a motor  130 . However, in some embodiments, the charger  105  and battery  110  may be used to power a different type of load. For example, although not illustrated in  FIG. 1 , the power supply system  100  may be included in a vehicle, such as a passenger vehicle, a motorcycle, a truck, a bus, or the like, where the drive unit  120  drives one or more wheels of the vehicle. Similarly, the battery  110  in this situation can be considered a primary battery of the vehicle used to drive or move the vehicle. However, in some embodiments, the drive unit  120  drives other components of a vehicle and the power supply system  100  described herein is not limited to supplying power to a motor  130  as illustrated in the example embodiment of  FIG. 1 . 
     The charger  105  includes a charging interface  135  coupled to the power source  115 , a rectifier  140 , and a converter  145  connected to the battery  110 . The rectifier  140  converts a power supply signal, such as an alternating current (AC) signal, from the power source  115 , which may be external to the vehicle when the power supply system  100  is included in a vehicle as described above, to a direct current (DC) signal. The converter  145  provides isolation between the power source  115  and the battery  110  and generates a charging signal for the battery  110 . The converter  145  also generates an auxiliary power supply signal for an auxiliary system  150  and isolates the auxiliary system  150  from the power source  115 . In some embodiments, where the power supply system  100  is implemented in a vehicle, the auxiliary system  150  includes loads such as, for example, a radio, a navigation system, a heating unit, an instrument cluster, control electronics for the vehicle, and the like. In some embodiments, the auxiliary system  150  includes an auxiliary battery distinct from the battery  110 . 
       FIG. 2  is a circuit diagram of one embodiment of the charger  105  included in the power supply system  100  of  FIG. 1 . Power from the power source  115  is received at the charging interface  135  and provided to the rectifier  140 . In some embodiments, the rectifier  140  is an active power factor correction rectifier. Other types of rectifiers, such as passive rectifiers, bridge rectifiers, or the like, may be used. As one example embodiment, the rectifier  140  includes inductors  155  and  160 , switching transistors  165 ,  170 ,  175 ,  180 ,  185 , and  190 , and an intermediate bus capacitor  195 . A controller  200  generates switching signals for the switching transistors  165 ,  170 ,  175 ,  180 ,  185 , and  190  for power factor correction of the AC power from the power source  115  and to generate a DC voltage on the intermediate bus capacitor  195 . For ease of illustration, connections between the controller  200  and the gate terminals of the switching transistors  165 ,  170 ,  175 ,  180 ,  185 , and  190  are omitted. Also, feedback signals, such as voltage across the intermediate bus capacitor  195  and input current used by the controller  200  are also omitted. 
     In general, the inductors  155  and  160  store energy from the power source  115  and the controller  200  controls the switching transistors  165 ,  170 ,  175 ,  180 ,  185 , and  190  to transfer power to the intermediate bus capacitor  195 , thereby controlling the DC voltage generated across the intermediate bus capacitor  195 . The controller  200  controls the duty cycle and switching frequency of the switching signals to control the current signal applied to the intermediate bus capacitor  195 . In some embodiments, the power source  115  provides a nominal AC voltage, such as 120V or 240V, and the rectifier  140  generates a DC voltage of about 400V on the intermediate bus capacitor  195 . 
     In one example embodiment, the converter  145  includes a transformer  205  including a primary winding  205 A, a secondary winding  205 B, and an auxiliary winding  205 C. In one example, the turns ratio of the primary winding  205 A to the secondary winding  205 B is about 15:14, and the turns ratio of the primary winding  205 A to the auxiliary winding  205 C is about 15:1. Resonant tanks  210 ,  215 , and  220  are coupled to the primary winding  205 A, the secondary winding  205 B, and the auxiliary winding  205 C, respectively. As illustrated in  FIG. 2 , the resonant tank  210  can include an inductor  210 A and a capacitor  210 B connected in series, the resonant tank  215  can include an inductor  215 A and a capacitor  215 B connected in series, and the resonant tank  220  can include an inductor  220 A and a capacitor  220 B connected in series. In one example embodiment, switching transistors  225 ,  230 ,  235 , and  240  are coupled between the intermediate bus capacitor  195  and the resonant tank  210 , and switching transistors  245 ,  250 ,  255 , and  260  are coupled between the resonant tank  215  and a primary bus capacitor  265 . The terminals of the primary bus capacitor  265  provide a battery interface  110 A for coupling to the battery  110  (e.g., via fuses  270  and  275 ). 
     In some embodiments, the auxiliary winding  205 C has a center tap, a diode  280  is coupled between the resonant tank  220  and an auxiliary bus capacitor  285 , and a diode  290  is coupled between the center tap of the auxiliary winding  205 C and the auxiliary bus capacitor  285 . The terminals of the auxiliary bus capacitor  285  provide an auxiliary system interface  150 A for coupling to the auxiliary system  150 . The diodes  280 ,  290  rectify the signal present on the center tap of the auxiliary winding  205 C. In some embodiments, the auxiliary winding  205 C does not include a center tap, and additional rectifying devices would be used, such as a full bridge diode rectifier or a full bridge transistor rectifier for synchronous rectification. 
     The controller  200  controls the switching transistors  225 ,  230 ,  235 , and  240  to transfer power to the primary bus capacitor  265 , thereby controlling the DC voltage generated across the primary bus capacitor  265 . The controller  200  controls the duty cycle and switching frequency of the switching signals to control the current signal applied to the primary bus capacitor  265 . In some embodiments, the converter  145  generates a DC voltage ranging from about 240V to about 403V across the primary bus capacitor  265 . For ease of illustration, connections between the controller  200  and the gate terminals of the switching transistors  225 ,  230 ,  235 ,  240 ,  245 ,  250 ,  255 , and  260  are omitted. Also, feedback signals, such as voltage across the primary bus capacitor  265 , battery current, and the like, used by the controller  200  are also omitted. 
     Current flowing through the primary winding  205 A and the secondary winding  205 B induces current in the auxiliary winding  205 C. As described in greater detail below, when attached to the power source  115 , the converter  145  uses power from the power source  115  to power the auxiliary system  150  through current induced in the auxiliary winding  205 C by the primary winding  205 A. When not attached to the power source  115 , the converter  145  uses power from the battery  110  to power the auxiliary system  150  through current induced in the auxiliary winding  205 C by the secondary winding  205 B. In some embodiments, the voltage generated across the auxiliary bus capacitor  285  varies from about 9V to about 14.5V. 
     When the charger  105  is coupled to the power source  115 , the converter  145  uses power from the power source  115  to supply current to charge the battery  110  and to power the auxiliary system  150 . In some embodiments, the controller  200  implements a constant frequency, variable duty cycle technique for controlling the rectifier  140  to generate the voltage across the intermediate bus capacitor  195 . The controller  200  can employ multiple modes for controlling the converter  145  to charge the battery  110 . In some embodiments, the controller  200  employs a variable frequency, constant duty cycle technique for controlling the converter  145  to generate the voltage across the primary bus capacitor  265 . A change in frequency changes the impedances of the resonant tanks  210 ,  215 , and  220 , which thereby changes current generated by the converter  145 . Depending on the algorithm used for control, one or more of the resonant tanks  210 ,  215 , and  220  may be omitted. For example, the resonant tank  210  may be used with the resonant tank  215  or the resonant tank  215 , or both. The mode used by the controller  200  can depend on the voltage and current associated with the battery  110 . In general, the controller  200  changes the frequency to change the current supplied to the battery  110  by the converter  145 . For example, in a first mode, the controller  200  employs a constant current mode for controlling the converter  145  to charge the battery  110  when the voltage of the battery  110  is less than the target voltage. In some embodiments, the target voltage is about 403V and the constant current is about 18 A. As the voltage across the battery  110  increases, the controller  200  limits the power provided to the battery  110  to avoid a thermal overload condition. In some embodiments, the controller  200  employs a power threshold of about 6.6 kW in a second charging mode. When the power reaches the power threshold, the controller  200  reduces the current generated by the converter  145  to provide a constant power charging signal. As the voltage of the battery  110  approaches the target value, the controller  200  implements a third charging mode using a constant voltage approach. The controller  200  controls the current generated by the converter  145  to provide a relatively constant voltage at the target voltage across the primary bus capacitor  265  and the battery  110 . 
     When the charger  105  is not coupled to the power source  115 , the converter  145  uses power from the battery  110  to supply current to power the auxiliary system  150 . Is this mode, the switching transistors  225 ,  230 ,  235 , and  240  are not used, but the controller  200  activates the switching transistors  245 ,  250 ,  255 , and  260  to generate a current in the secondary winding  205 B that induces a current in the auxiliary winding  205 C to generate a voltage across the auxiliary bus capacitor  285  to power the auxiliary system  150 . Similar to the charging mode, the controller  200  can implement a variable frequency, constant duty cycle technique for controlling the switching transistors  245 ,  250 ,  255 , and  260  to generate the voltage across the auxiliary bus capacitor  285 . In some embodiments, controller  200  employs the multiple modes described above for controlling the switching transistors  245 ,  250 ,  255 , and  260  for generating the voltage across the auxiliary bus capacitor  285 . A change in frequency changes the impedances of the resonant tanks  215  and  220 , which thereby changes current generated by the converter  145 . 
       FIG. 3  is a circuit diagram of another embodiment of the charger  105  included in the power supply system  100  of  FIG. 1  for charging the battery  110  and powering the auxiliary system  150 . In  FIG. 3 , an auxiliary battery  300  is illustrated as being coupled to the auxiliary bus capacitor  285 . The diodes  280  and  290  illustrated in  FIG. 2  are replaced with transistors  305  and  310 . The transistors  305  and  310  allow synchronous rectification to increase the efficiency of the charger  105  of  FIG. 3  as compared to the charger  105  of  FIG. 2 . In some embodiments, a transistor  315  is placed in series with the auxiliary battery  300  to avoid overcharging or to tune the charging current provided to the auxiliary battery  300 . For example, the controller  200  may control the duty cycle of the transistor  315  to tune the current when the charger  105  is coupled to the power source  115  and the controller  200  controls the current generated by the converter  145  based on the parameters of the battery  110 . 
     The converter  145  described herein shares circuitry for charging the battery  110  with that for powering the auxiliary system  150 . Hence, a separate power converter module is not required for generating the auxiliary voltage. This arrangement reduces the chip count and cost of the charger  105 . 
     Various features and advantages of the invention are set forth in the following claims.