Power reception device

Abstract

To provide a power reception device capable of suppressing a surge at a time of reconduction.SOLUTION: A power reception device that receives a power transmitted from a power transmission device in a non-contact manner, includes a cutoff circuit that is used during protection control and electrically cuts off a power reception coil and a battery. The cutoff circuit includes a first relay provided between the power reception coil and the battery, a second relay provided on a second power line branched from the first power line connecting the power reception coil and the first relay, a discharge resistor provided between the second relay and a ground, a first comparator that outputs the first relay to open the first relay when a voltage exceeds a predetermined output threshold. and a second comparator that outputs the second relay to close the second relay when a voltage exceeds a predetermined output threshold. The output threshold of the second comparator is set to a voltage lower than the output threshold of the first comparator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power receiving device. [Background technology]

[0002] Patent Document 1 discloses that a power transmitting device that transmits power to a power receiving device in a contactless manner includes a control unit that executes power transmission stop control to stop the output of an inverter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-158066 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the configuration described in Patent Document 1, a surge voltage occurs when an abnormality occurs, which may cause damage to the power receiving device and components in its peripheral devices.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a power receiving device that can suppress surges when re-conduction occurs. [Means for solving the problem]

[0006] The present invention provides a power receiving device that receives power transmitted wirelessly from a power transmitting device, and includes an interruption circuit that is used during protective control and electrically interrupts a receiving coil and a battery, the interruption circuit including a first relay provided between the receiving coil and the battery, a second relay provided on a second power line branching off from a first power line connecting the receiving coil and the first relay, a discharge resistor provided between the second relay and ground, a first comparator that outputs to the first relay to open the first relay when a voltage exceeds a predetermined output threshold, and a second comparator that outputs to the second relay to close the second relay when a voltage exceeds the predetermined output threshold, and the output threshold of the second comparator is set to a voltage lower than the output threshold of the first comparator. [Effects of the Invention]

[0007] In the present invention, it is possible to suppress surges when the current is restored. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a contactless charging system according to an embodiment. [Figure 2] FIG. 2 is a time chart for explaining the state when conduction is resumed. DETAILED DESCRIPTION OF THE INVENTION

[0009] The power receiving device according to the embodiment of the present invention will be specifically described below, but the present invention is not limited to the embodiment described below.

[0010] 1 is a diagram showing a contactless charging system according to an embodiment. The contactless charging system 1 includes a power transmitting device 2 and a power receiving device 3.

[0011] The power transmitting device 2 transmits power to the power receiving device 3 in a contactless manner. The power transmitting device 2 includes an electric circuit electrically connected to an AC power source 4. The power transmitting device 2 includes a rectifier unit 11, a chopper control unit 12, an inverter control unit (INV control unit) 13, a power transmitting coil 14, a communication unit 15, a current / voltage control unit 16, a current sensor 17, and a voltage sensor 18.

[0012] The rectifier 11 converts the AC voltage supplied from the AC power source 4 into a DC voltage and outputs it to the chopper control unit 12. The chopper control unit 12 controls the DC voltage input from the rectifier 11 to a predetermined voltage value or current value and outputs it to the inverter control unit 13. The inverter control unit 13 converts the DC voltage input from the chopper control unit 12 into an AC voltage of an arbitrary frequency and outputs it to the power transmission coil 14. The power transmission coil 14 is a primary coil that transmits power contactlessly. The communication unit 15 communicates wirelessly with the communication unit 24 of the power receiving device 3.

[0013] Current / voltage control unit 16 controls the charging power. Current / voltage control unit 16 controls chopper control unit 12 and inverter control unit 13 based on the current value from current sensor 17 and the voltage value from voltage sensor 18. Signals from current sensor 17 and voltage sensor 18 are input to current / voltage control unit 16. Current sensor 17 detects the current flowing from chopper control unit 12 to inverter control unit 13 and outputs the current value to current / voltage control unit 16. Voltage sensor 18 detects the voltage applied to inverter control unit 13 and outputs the voltage value to current / voltage control unit 16. Current / voltage control unit 16 monitors the current value detected by current sensor 17 and the voltage value detected by voltage sensor 18.

[0014] The power receiving device 3 receives power transmitted contactlessly from the power transmitting device 2. The power receiving device 3 supplies the power supplied from the power transmitting device 2 to a battery pack 5. The battery pack 5 stores the power supplied from the power receiving device 3. The battery pack 5 is electrically connected to the power receiving device 3 and is also electrically connected to a motor (MG) 7 via an MG driver 6. The power receiving device 3, battery pack 5, and motor 7 are mounted on an AGV or AMR used for logistics in factories, warehouses, etc. For example, the power receiving device 3, battery pack 5, and motor 7 are mounted on auxiliary battery-less robotics, micromobility, etc.

[0015] The power receiving device 3 includes a power receiving coil 21 , a rectifier 22 , a cutoff circuit 23 , a communication unit 24 , and a control unit 25 .

[0016] The receiving coil 21 is a secondary coil that receives power transmitted contactlessly from the transmitting coil 14. When a current flows through the transmitting coil 14, a magnetic field is formed around the transmitting coil 14, and a current flows through the receiving coil 21 due to electromagnetic induction around the transmitting coil 14. The rectifier 22 converts the AC voltage input from the receiving coil 21 into a DC voltage and outputs it to the interrupter circuit 23. The rectifier 22 supplies power to the battery pack 5 via the interrupter circuit 23. The communication unit 24 communicates wirelessly with the communication unit 15 of the power transmitter 2.

[0017] Control unit 25 controls rectification unit 22 based on the current value from current sensor 26 and the voltage value from voltage sensor 27. Control unit 25 receives signals from current sensor 26 and voltage sensor 27. Current sensor 26 detects the current flowing from power receiving coil 21 to rectification unit 22 and outputs the current value to control unit 25. Voltage sensor 27 detects the voltage applied to rectification unit 22 and outputs the voltage value to control unit 25. Control unit 25 monitors the current value detected by current sensor 26 and the voltage value detected by voltage sensor 27.

[0018] The interrupter circuit 23 is provided between the rectifier unit 22 and the battery pack 5. The interrupter circuit 23 is a passive type interrupter circuit. The interrupter circuit 23 is used during protection control, and electrically disconnects the power receiving coil 21 from the battery pack 5.

[0019] The interrupter circuit 23 includes a first relay 31, a second relay 32, a discharge resistor 33, a first comparator 34, and a second comparator 35.

[0020] The first relay 31 is provided between the power receiving coil 21 and the battery pack 5. The first relay 31 is provided on the first power line 36 between the rectifier unit 22 and the battery pack 5. The first relay 31 is configured by an enhancement type MOS-FET.

[0021] The second relay 32 is provided between the power receiving coil 21 and the ground. The second relay 32 is provided on a second power line 37 branching off from the first power line 36. The second relay 32 is configured by a depression type MOS-FET. The discharge resistor 33 is provided between the second relay 32 and the ground. The discharge resistor 33 is connected in series with the second relay 32.

[0022] The first comparator 34 is a comparator that outputs to the first relay 31. When the voltage exceeds a predetermined output threshold, the first comparator 34 outputs to the first relay 31 to open the first relay 31. For example, the output threshold of the first comparator 34 is set to 60 V. The first relay 31 and the first comparator 34 are used in sequence control and protection control.

[0023] The second comparator 35 is a comparator that outputs to the second relay 32. When the voltage exceeds a predetermined output threshold, the second comparator 35 outputs to the second relay 32 to close the second relay 32. For example, the output threshold of the second comparator 35 is set to 50 V. The output threshold of the second comparator 35 is set to a voltage lower than the output threshold of the first comparator 34. The second relay 32, the discharge resistor 33, and the second comparator 35 are used in protection control.

[0024] The battery pack 5 includes a battery 41, relays 42 and 43, a battery control unit 44, a current sensor 45, and a voltage sensor .

[0025] The battery 41 is a secondary battery that stores the power supplied from the power receiving device 3. The battery 41 is electrically connected to the power receiving coil 21 via the interrupter circuit 23. The battery 41 is a driving battery for the AGV or AMR, and is a DC power supply that supplies power to the motor 7. The relays 42 and 43 are relays provided in the battery pack 5.

[0026] The battery control unit 44 controls the relays 42 and 43 based on the current value from the current sensor 45 and the voltage value from the voltage sensor 46. The battery control unit 44 outputs commands to the relays 42 and 43. The battery control unit 44 receives detection signals from the current sensor 45 and the voltage sensor 46. The current sensor 45 detects the current of the battery 41 and outputs the current value to the battery control unit 44. The voltage sensor 46 detects the voltage of the battery 41 and outputs the voltage value to the battery control unit 44. The battery control unit 44 monitors the current value detected by the current sensor 45 and the voltage value detected by the voltage sensor 46.

[0027] In the power receiving device 3, when an abnormality occurs, the battery control unit 44 may instruct the relays 42 and 43 in the battery pack 5 to be OPEN (load dump). The interrupter circuit 23 functions as a circuit to remove a surge that occurs when the power is restored to electrical continuity.

[0028] Fig. 2 is a time chart for explaining the state at the time of re-energization. Fig. 2 shows the charging state (AGV state) of the power receiving device 3, the states of the relays 42 and 43 in the battery pack 5, the voltage between the power receiving coil 21 and the battery pack 5, the current between the power receiving coil 21 and the battery pack 5, the state of the first comparator 34, and the state of the second comparator 35.

[0029] 2, when the voltage between the power receiving coil 21 and the battery pack 5 exceeds a control switching voltage while the battery pack 5 is being charged with power supplied from the power receiving device 3, the charging state switches from constant current charging (CC charging) to constant voltage charging (CV charging) (time t1). Then, due to a disturbance such as noise, the battery control unit 44 (BMS) in the battery pack 5 being charged opens the relays 42 and 43 in the battery pack 5, interrupting the conduction path (time t2). Charging stops when the conduction path is interrupted.

[0030] After charging stops, when the voltage between the power receiving coil 21 and the battery pack 5 exceeds the output threshold (activation threshold) of the second comparator 35, the second comparator 35 outputs and closes the second relay 32 (time t3). As shown in FIG. 2, the output threshold of the second comparator 35 is lower than the output threshold of the first comparator 34. At time t3, the second comparator 35 switches from low to high and outputs to the second relay 32, causing the second relay 32 to switch from an open state (OPEN) to a closed state (CLOSE). After time t3, the rate of increase in voltage slows down due to the closure of the second relay 32.

[0031] After the second relay 32 is closed, when the voltage between the power receiving coil 21 and the battery pack 5 exceeds the output threshold (activation threshold) of the first comparator 34, the first comparator 34 outputs and opens the first relay 31 (time t4). At time t4, the first comparator 34 switches from Low to Hi and outputs to the first relay 31, causing the first relay 31 to switch from a closed state (CLOSE) to an open state (OPEN).

[0032] After time t4, the first relay 31 opens, causing forced discharge by the discharge resistor 33. In the voltage graph, the solid line L1 represents the voltage between the first relay 31 and the battery 41, and the dashed line L2 represents the voltage between the power receiving coil 21 and the first relay 31. When the first relay 31 opens at time t4, the conduction path from the power receiving coil 21 to the battery 41 is interrupted, so the voltage between the first relay 31 and the battery pack 5 becomes 0 V, as shown by the solid line L1. However, even though the first relay 31 opens at time t4, the conduction path from the power receiving coil 21 to the first relay 31 is not interrupted, so the voltage between the power receiving coil 21 and the first relay 31 becomes higher than the output threshold of the first comparator 34, as shown by the dashed line L2. A voltage drop occurs in the voltage between the power receiving coil 21 and the first relay 31 due to forced discharge by the discharge resistor 33, and the charge is released. As a result of this forced discharge, the charge is released, and the voltage between the power receiving coil 21 and the first relay 31 changes from rising to falling and drops rapidly.

[0033] After the first relay 31 is opened, a voltage drop occurs due to forced discharge by the discharge resistor 33, and when the voltage between the power receiving coil 21 and the first relay 31 falls below the output threshold of the first comparator 34, the first comparator 34 outputs and closes the first relay 31 (time t5). Time t5 is the time when conduction resumes. At time t5, the first comparator 34 switches from Hi to Low and outputs to the first relay 31, causing the first relay 31 to switch from an open state (OPEN) to a closed state (CLOSE).

[0034] After the first relay 31 is closed (after re-conduction), when the voltage between the power receiving coil 21 and the battery pack 5 falls below the output threshold of the second comparator 35, the second comparator 35 outputs and opens the second relay 32 (time t6). At time t6, the second comparator 35 switches from Hi to Low and outputs to the second relay 32, causing the second relay 32 to switch from a closed state (CLOSE) to an open state (OPEN).

[0035] In this way, in the power receiving device 3, the second comparator 35 outputs before the first comparator 34 and closes the second relay 32, and then the first comparator 34 outputs and opens the first relay 31. Due to the forced discharge by the discharge resistor 33, the charge is released (the voltage drops rapidly) when the power is re-connected. The first comparator 34 outputs before the second comparator 35 and closes the first relay 31, and then the second comparator 35 outputs and opens the second relay 32. Because the charge in the entire conduction path is released at the time the first relay 31 closes (re-connects), a surge voltage is not applied to the entire system.

[0036] As described above, according to the embodiment, the interrupter circuit 23 functions as a circuit for removing a surge when conduction is restored, and therefore, a surge when conduction is restored in the power receiving device 3 can be suppressed. [Explanation of symbols]

[0037] 1. Wireless charging system 2. Power transmission equipment 3 Power receiving device 5 Battery pack 23 Breaking Circuit 31 1st Relay 32 Second Relay 33 Discharge resistor 34 First Comparator 35 Second Comparator

Claims

[Claim 1] A power receiving device that receives power transmitted contactlessly from a power transmitting device, A circuit breaker is provided which is used during protection control and electrically cuts off the receiving coil and the battery. The interruption circuit includes: a first relay provided between the receiving coil and the battery; a second relay provided on a second power line branching from a first power line connecting the power receiving coil and the first relay; a discharge resistor provided between the second relay and ground; a first comparator that outputs an output to the first relay to open the first relay when the voltage exceeds a predetermined output threshold; a second comparator that outputs to the second relay to close the second relay when the voltage exceeds a predetermined output threshold; The output threshold of the second comparator is set to a voltage lower than the output threshold of the first comparator. A power receiving device characterized by:

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