An auxiliary source monitoring circuit and an on-board charger

Abstract

The application discloses an auxiliary source monitoring circuit and a vehicle-mounted charger. The auxiliary source monitoring circuit comprises a high-power switch tube module, a high-voltage battery, an internal auxiliary source module, a signal control module, an isolation driving module, an isolation auxiliary source module and an auxiliary source monitoring module. The internal auxiliary source module supplies power to the signal control module. The signal control module generates a PWM driving signal. The isolation driving module drives the high-power switch tube module after isolating and amplifying the PWM driving signal. The isolation auxiliary source module supplies power to the isolation driving module. The auxiliary source monitoring module collects power supply signals of an external low-voltage power supply G output end and the internal auxiliary source module C output end, and controls whether the signal control module continues to output the PWM driving signal according to the change of the power supply signal level. The application can monitor the internal auxiliary source module and the isolation auxiliary source module, and ensure that the vehicle-mounted charger can timely cut off the control signal of the high-power switch tube when the external power supply is abnormal.

Description

Technical Field

[0001] The present invention relates to the field of charging and electric driving, and mainly relates to an auxiliary source monitoring circuit and an on-board charger. Background Art

[0002] Driven by energy conservation, emission reduction, and the need to control air pollution, new energy vehicles are gradually gaining commercial popularity, with electric vehicles being the primary force behind them. With the widespread adoption of new energy vehicles, the safety and reliability of on-board chargers (OBCs) has become a growing concern. High-power switching transistors, the primary components in OBCs, are sensitive to supply voltage and are a major source of failure. Consequently, monitoring the supply voltage of high-power switching transistors and protecting the entire system are crucial. Summary of the Invention

[0003] In order to solve the above-mentioned defects in the prior art, the present invention provides an auxiliary source monitoring circuit and an on-board charger.

[0004] The technical solution adopted by the present invention is to design an auxiliary source monitoring circuit, including a high-power switch tube module connected to an external high-voltage power supply, a high-voltage battery that receives DC power transmission from the high-power switch tube module, and an internal auxiliary source module, a signal control module, an isolation drive module, and an isolation auxiliary source module and an auxiliary source monitoring module connected in sequence; the internal auxiliary source module is connected to an external low-voltage power supply, converts the electric energy of the external low-voltage power supply into low-voltage DC signals of different levels to power the control module; the signal control module is used to generate a PWM drive signal; the isolation drive module is used to isolate the signal control module, isolate and amplify the PWM drive signal, and then drive the high-power switch tube module; the isolated auxiliary source module is connected to the external low-voltage power supply, converts the electric energy of the external low-voltage power supply into DC power to power the isolation drive module; the auxiliary source monitoring module collects the power supply signals of the output end G of the external low-voltage power supply and the output end C of the internal auxiliary source module, and controls whether the signal control module continues to output the PWM drive signal according to the change of the power supply signal level.

[0005] The auxiliary source monitoring module is powered by an isolated auxiliary source module, which includes an isolation transformer. The isolated power supply input winding L1 of the isolation transformer is connected to an external low-voltage power supply. The isolation transformer has a drive module power supply winding L2 and a monitoring module power supply winding L3. The drive module power supply winding L2 supplies power to the isolated drive module through the rectifier module and the A output end, and the monitoring module power supply winding L3 supplies power to the auxiliary source monitoring module through the rectifier module and the B output end.

[0006] The auxiliary source monitoring module collects the power supply signal of the output end of the isolated auxiliary source module B, as well as the power supply signals of the output end of the external low-voltage power supply G and the output end of the internal auxiliary source module C, and controls whether the signal control module continues to output the PWM drive signal according to the changes in the power supply signal level.

[0007] The power supply signal is a voltage signal. The voltage acquisition device arranged at the output end of the isolated auxiliary source module B is used to collect the voltage at point B, the voltage acquisition device arranged at the output end of the external low-voltage power supply G is used to collect the voltage at point G, and the voltage acquisition device arranged at the output end of the internal auxiliary source module C is used to collect the voltage at point C.

[0008] The auxiliary source monitoring module is equipped with an input voltage protection threshold, an isolated auxiliary source module voltage protection threshold and an internal auxiliary source module voltage protection threshold. When the voltage at point G is lower than the input voltage protection threshold, or the voltage at point B is lower than the isolated auxiliary source module voltage protection threshold, or the voltage at point C is lower than the internal auxiliary source module voltage protection threshold, the auxiliary source monitoring module controls the signal control module to stop outputting the PWM drive signal.

[0009] The high-power switch tube module adopts a three-phase full-bridge topology structure including six switch tubes forming three bridge arms.

[0010] The external low-voltage power supply is a low-voltage direct current, and the internal auxiliary power module adopts a DCDC module.

[0011] The external low-voltage power supply is a low-voltage alternating current, and the internal auxiliary source module adopts an ACDC module.

[0012] There are multiple high-power switch tube modules and isolation drive modules, and the number is the same. One isolation drive module drives one high-power switch tube module. The auxiliary source monitoring module is powered by the isolation auxiliary source module. The isolation auxiliary source module includes an isolation transformer. The isolation power supply input winding L1 of the isolation transformer is connected to an external low-voltage power supply. The isolation transformer has a monitoring module power supply winding L3 and multiple drive module power supply windings (L21...L2n). The drive module power supply windings supply power to the corresponding isolation drive module through their respective rectifier modules and output ends. The monitoring module power supply winding L3 supplies power to the auxiliary source monitoring module through the rectifier module and the B output end.

[0013] The auxiliary source monitoring module is powered by an isolated auxiliary source module, which includes an isolation transformer. The isolated power supply input winding L1 of the isolation transformer is connected to an external low-voltage power supply. The isolation transformer has a drive module power supply winding L2 and at least two monitoring module power supply windings (L31...L3n). The drive module power supply winding L2 supplies power to the isolated drive module through the rectifier module and the A output terminal, and the monitoring module power supply windings supply power to the auxiliary source monitoring module through their respective rectifier modules and output terminals.

[0014] The present invention also provides an on-board charger, which uses the auxiliary source monitoring circuit described above. Single-phase or three-phase mains electricity, and the high-voltage battery is an on-board high-voltage battery.

[0015] The beneficial effects of the technical solution provided by the present invention are:

[0016] Aiming at the demand for monitoring the auxiliary source drive power supply of the high-power switch tube of the on-board charger, the present invention provides an auxiliary power supply monitoring system, which can monitor the internal auxiliary source module and the isolated auxiliary source module of the high-power switch tube of the on-board charger, ensuring that when the external power supply of the on-board charger is abnormal, the control signal of the high-power switch tube can be cut off in time to avoid failure of the on-board charger; in addition, when a single high-power switch tube fails, the auxiliary source monitoring module can provide timely protection to avoid power supply to the on-board charger or internal control module, and when the drive power supply is abnormal, more devices will fail, or other components of the entire vehicle will fail. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is described in detail below with reference to the embodiments and accompanying drawings, in which:

[0018] Figure 1 It is a principle block diagram of a preferred embodiment of the present invention;

[0019] Figure 2 is a schematic diagram of an isolation transformer in a preferred embodiment of the present invention;

[0020] Figure 3 This is the timing diagram of the operation of the auxiliary source monitoring circuit under power supply failure conditions;

[0021] Figure 4 This is the timing diagram of the installed auxiliary source monitoring circuit operating under power supply failure conditions;

[0022] Figure 5 A circuit for monitoring auxiliary sources of multiple high-power switch tube modules;

[0023] Figure 6 A schematic diagram of an isolation transformer in an embodiment of multiple high-power switch tube modules;

[0024] Figure 7A monitoring circuit having a plurality of monitoring module power supply windings;

[0025] Figure 8 This is a schematic diagram of an isolation transformer with power supply windings for multiple monitoring modules. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0027] The present invention discloses an auxiliary source monitoring circuit, see Figure 1 The principle block diagram of a preferred embodiment of the present invention is shown, in which the auxiliary source monitoring circuit includes a high-power switch tube module connected to an external high-voltage power supply, a high-voltage battery that receives DC power transmission from the high-power switch tube module, and an internal auxiliary source module, a signal control module, an isolation drive module, an isolation auxiliary source module, and an auxiliary source monitoring module connected in sequence; the internal auxiliary source module is connected to an external low-voltage power supply and converts the power of the external low-voltage power supply into low-voltage DC signals of different levels to power the control module; the signal control module is used to generate a PWM drive signal; the isolation drive module is used to isolate the signal control module, isolate and amplify the PWM drive signal, and then drive the high-power switch tube module; the isolated auxiliary source module is connected to the external low-voltage power supply and converts the power of the external low-voltage power supply into DC power to power the isolation drive module; the auxiliary source monitoring module collects power supply signals from the output end G of the external low-voltage power supply and the output end C of the internal auxiliary source module, and controls whether the signal control module continues to output the PWM drive signal according to changes in the power supply signal level.

[0028] See Figure 1This embodiment of the present invention in an electric vehicle illustrates a device. Q1, Q2, Q3, Q4, Q5, and Q6 are high-power switches in the onboard charger. Their primary function is to convert the high-voltage AC input from an external power supply into DC power for energy storage in the electric vehicle's battery. Drive circuit F is the PWM drive signal output by the isolation drive module, and its primary function is to drive the high-power switches. Drive circuit E is the output drive signal from the signal control module and the input signal to the isolation drive module. Its primary function is to provide the drive signal to the isolation drive module for signal conversion. As the primary module in the onboard charger, the high-power switches convert the external high-voltage AC input power into high-voltage DC power for energy storage in the electric vehicle's battery. The high-power switches are controlled by the signal control module based on sampled information. Since the high-power switches are driven by high-voltage signals, while the signal control module is driven by low-voltage signals, the isolation drive module is required to convert the PWM drive signals. Therefore, the power supply for the isolation drive module and the signal control module requires independent auxiliary power modules.

[0029] The auxiliary source monitoring module is powered by the isolated auxiliary source module, see Figure 2 The schematic diagram of the isolation transformer in the preferred embodiment is shown. The isolated auxiliary source module includes an isolation transformer, whose isolated power supply input winding L1 is connected to an external low-voltage power supply. The isolation transformer has a drive module power supply winding L2 and a monitoring module power supply winding L3. The drive module power supply winding L2 supplies power to the isolated drive module via the rectifier module and output terminal A, while the monitoring module power supply winding L3 supplies power to the auxiliary source monitoring module via the rectifier module and output terminal B. The voltage withstand design requirements between L1, L2, and L3 are met. By monitoring the voltage of the L3 winding, it is possible to monitor abnormal voltages in the L2 winding. This auxiliary source voltage monitoring method has a cost advantage over direct voltage monitoring, while also achieving an isolated design for auxiliary source monitoring.

[0030] The auxiliary source monitoring module collects the power supply signal of the output end of the isolated auxiliary source module B, as well as the power supply signals of the output end of the external low-voltage power supply G and the output end of the internal auxiliary source module C, and controls whether the signal control module continues to output the PWM drive signal according to the changes in the power supply signal level.

[0031] In a preferred embodiment, the power supply signal is a voltage signal, and the voltage acquisition device arranged at the output end of the isolated auxiliary source module B is used to collect the voltage at point B, the voltage acquisition device arranged at the output end of the external low-voltage power supply G is used to collect the voltage at point G, and the voltage acquisition device arranged at the output end of the internal auxiliary source module C is used to collect the voltage at point C.

[0032] In a preferred embodiment, the auxiliary source monitoring module is provided with an input voltage protection threshold, an isolated auxiliary source module voltage protection threshold, and an internal auxiliary source module voltage protection threshold. When the voltage at point G is lower than the input voltage protection threshold, or the voltage at point B is lower than the isolated auxiliary source module voltage protection threshold, or the voltage at point C is lower than the internal auxiliary source module voltage protection threshold, the auxiliary source monitoring module controls the signal control module to stop outputting the PWM drive signal. In actual use, when the auxiliary source monitoring module detects a charger fault, it will generate a protection flag signal ( Figure 1 Signal D) sends a signal to the signal control module, and the signal control module stops outputting the PWM drive signal.

[0033] See Figure 1 In the preferred embodiment shown, the high-power switch module includes, but is not limited to, a three-phase full-bridge topology, a single-phase topology, an electric three-phase drive system, and other high-power bridge topologies. The external low-voltage power supply is a low-voltage direct current (DC), and the internal auxiliary power module utilizes a DC-DC module. The external low-voltage power supply is a low-voltage alternating current (AC), and the internal auxiliary power module utilizes an AC-DC module.

[0034] The following combination Figure 1 and Figure 2 The working principle of the present invention is further explained.

[0035] The present invention directly monitors the voltage at point C, the output terminal of the internal auxiliary power module C. When the voltage at point C becomes abnormal, the auxiliary power monitoring module identifies the fault and transmits this information to the signal control module via auxiliary power fault signal D. The signal control module then cuts off its output control signal E to shut down the high-power switching module, ensuring the safety of the onboard charger and the vehicle.

[0036] The present invention monitors the voltage at point A on the output of the isolated auxiliary source module A indirectly. Because the voltage at point A is the power supply for the isolated driver module and belongs to the high-voltage module, the auxiliary source monitoring module cannot directly monitor and detect it. The power supply signal from the external low-voltage auxiliary source, passing through the isolation transformer and rectifier bridge, creates the voltages at points A and B. Since the voltage at point B and the voltage at point A belong to different windings of the isolated auxiliary source, direct monitoring of the voltage at point B enables indirect monitoring of the voltage at point A. Once an abnormal voltage at point B is detected, the signal is transmitted to the signal control module via auxiliary source fault signal D. Therefore, the signal control module disconnects the control signal before the voltage at point A drops below the power transistor failure level, protecting the high-power switching transistor module. The voltage at point G is the monitoring signal of the external low-voltage power supply. By monitoring the three power supply monitoring signals G, B, and C, the entire low-voltage power supply module (including isolated and non-isolated power supply) of the on-board charger can be monitored, thereby protecting the entire power module and low-voltage module.

[0037] Figure 3 This is a timing diagram of the operation under power supply failure conditions without the auxiliary power monitoring circuit installed. When a power supply signal failure occurs, the signal control module cannot promptly receive fault information and maintains normal output of the drive control signal. In this state, the supply voltage to the isolated drive control module gradually decreases, causing the drive signal level of the high-power switching transistor to gradually decrease. High-power switching transistors are sensitive to drive levels and are prone to power thermal failure when the drive level is outside the required range.

[0038] Figure 4 This is the timing diagram of the operation of the installed auxiliary source monitoring circuit under power supply failure conditions. When the isolated auxiliary source fails, the auxiliary source monitoring module can promptly detect the power supply failure by monitoring the voltage at point B and trigger the fault signal D, which is transmitted to the signal control module. The signal control module can cut off the control signal input of the power transmission module before the drive level of the high-power switch tube drops to the failure level, thereby protecting the high-power switch tube and avoiding damage to a larger area of ​​the vehicle charger.

[0039] The auxiliary source monitoring circuit provided by the present invention can realize the monitoring and protection of the isolated power supply of the high-voltage system by the low-voltage system, and can be used in application scenarios including but not limited to vehicle chargers, vehicle DC converters, electric drive control systems, etc. Figure 5 A circuit for monitoring the auxiliary sources of multiple high-power switch tube modules is shown. The high-power switch tube modules (1-n) and the isolation drive modules (1-n) are multiple and the number is the same. One isolation drive module drives one high-power switch tube module, and one high-power switch tube module is connected to a high-voltage battery. The auxiliary source monitoring module is powered by the isolation auxiliary source module. Figure 6 The schematic diagram of the isolation transformer in the embodiment of multiple high-power switch tube modules is shown. The isolation auxiliary source module includes an isolation transformer. The isolation power input winding L1 of the isolation transformer is connected to the external low-voltage power supply. The isolation transformer has a monitoring module power supply winding L3 and multiple drive module power supply windings (L21...L2n). The drive module power supply windings supply power to the corresponding isolation drive module through their respective rectifier modules and output terminals. The monitoring module power supply winding L3 supplies power to the auxiliary source monitoring module through the rectifier module and the B output terminal. Figure 5 and Figure 6 The driving module power supply winding L21 corresponds to the isolated driving module 1, and the driving module power supply winding L2n corresponds to the isolated driving module n.

[0040] Figure 7 A monitoring circuit with multiple monitoring module power supply windings is shown, wherein the auxiliary source monitoring module is powered by an isolated auxiliary source module. Figure 8The schematic diagram of an isolation transformer with multiple monitoring module power supply windings is shown. The isolated auxiliary source module includes an isolation transformer whose isolated power supply input winding L1 is connected to an external low-voltage power supply. The isolation transformer has a drive module power supply winding L2 and at least two monitoring module power supply windings (L31...L3n). The drive module power supply winding L2 supplies power to the isolated drive module through the rectifier module and output terminal A, and the monitoring module power supply windings supply power to the auxiliary source monitoring module through their respective rectifier modules and output terminals. Figure 7 and Figure 8 There are at least two windings, L31 and L3n, that supply power to the monitoring module. This is due to the need for dual backup of detection lines and windings to avoid inaccurate detection caused by a monitoring module power supply winding or line being broken.

[0041] The present invention also discloses an on-board charger, which adopts the auxiliary source monitoring circuit.

[0042] In a preferred embodiment, the mains power is single-phase or three-phase, and the high-voltage battery is a vehicle-mounted high-voltage battery.

[0043] The above embodiments are for illustration only and are not intended to be limiting. Any equivalent modifications or variations made thereto without departing from the spirit and scope of this application should be included in the scope of the claims of this application.

Claims

1. An auxiliary power monitoring circuit, comprising a high-power switch module connected to an external high-voltage power supply and a high-voltage battery receiving DC power from the high-power switch module, characterized in that: It also includes an internal auxiliary source module, a signal control module, an isolation drive module, an isolation auxiliary source module and an auxiliary source monitoring module connected in sequence; The internal auxiliary source module is connected to an external low-voltage power supply, converting the electric energy of the external low-voltage power supply into low-voltage direct current signals of different levels to supply power to the control module; The signal control module is used to generate a PWM drive signal; The isolation drive module is used to isolate the signal control module, isolate and amplify the PWM drive signal and then drive the high-power switch tube module; The isolation auxiliary source module is connected to the external low-voltage power supply and converts the electric energy of the external low-voltage power supply into direct current to supply power to the isolation drive module; The auxiliary source monitoring module collects the power supply signals from the G output terminal of the external low-voltage power supply and the C output terminal of the internal auxiliary source module, and controls whether the signal control module continues to output the PWM drive signal according to the change in the level of the power supply signal; The auxiliary source monitoring module is powered by an isolated auxiliary source module, which includes an isolation transformer. The isolated power supply input winding L1 of the isolation transformer is connected to an external low-voltage power supply. The isolation transformer has a drive module power supply winding L2 and a monitoring module power supply winding L3. The drive module power supply winding L2 supplies power to the isolated drive module through the rectifier module and the A output terminal, and the monitoring module power supply winding L3 supplies power to the auxiliary source monitoring module through the rectifier module and the B output terminal; The high-power switch tube module adopts a three-phase full-bridge topology structure including six switch tubes forming three bridge arms.

2. The auxiliary source monitoring circuit according to claim 1, wherein: The auxiliary source monitoring module collects the power supply signal of the output end of the isolated auxiliary source module B, as well as the power supply signals of the output end of the external low-voltage power supply G and the output end of the internal auxiliary source module C, and controls whether the signal control module continues to output the PWM drive signal according to the changes in the power supply signal level.

3. The auxiliary source monitoring circuit according to claim 2, wherein: The power supply signal is a voltage signal. The voltage acquisition device arranged at the output end of the isolated auxiliary source module B is used to collect the voltage at point B, the voltage acquisition device arranged at the output end of the external low-voltage power supply G is used to collect the voltage at point G, and the voltage acquisition device arranged at the output end of the internal auxiliary source module C is used to collect the voltage at point C.

4. The auxiliary source monitoring circuit according to claim 3, wherein: The auxiliary source monitoring module is equipped with an input voltage protection threshold, an isolated auxiliary source module voltage protection threshold and an internal auxiliary source module voltage protection threshold. When the voltage at point G is lower than the input voltage protection threshold, or the voltage at point B is lower than the isolated auxiliary source module voltage protection threshold, or the voltage at point C is lower than the internal auxiliary source module voltage protection threshold, the auxiliary source monitoring module controls the signal control module to stop outputting the PWM drive signal.

5. The auxiliary source monitoring circuit according to claim 1, wherein: The external low-voltage power supply is a low-voltage direct current, and the internal auxiliary power module adopts a DCDC module.

6. The auxiliary source monitoring circuit according to claim 1, wherein: The external low-voltage power supply is a low-voltage alternating current, and the internal auxiliary source module adopts an ACDC module.

7. The auxiliary source monitoring circuit according to claim 1, wherein: There are multiple high-power switch tube modules and isolation drive modules, and the number is the same. One isolation drive module drives one high-power switch tube module. The auxiliary source monitoring module is powered by the isolation auxiliary source module. The isolation auxiliary source module includes an isolation transformer. The isolation power supply input winding L1 of the isolation transformer is connected to an external low-voltage power supply. The isolation transformer has a monitoring module power supply winding L3 and multiple drive module power supply windings (L21...L2n). The drive module power supply windings supply power to the corresponding isolation drive module through their respective rectifier modules and output ends. The monitoring module power supply winding L3 supplies power to the auxiliary source monitoring module through the rectifier module and the B output end.

8. The auxiliary source monitoring circuit according to claim 1, wherein: The auxiliary source monitoring module is powered by an isolated auxiliary source module, which includes an isolation transformer. The isolated power supply input winding L1 of the isolation transformer is connected to an external low-voltage power supply. The isolation transformer has a drive module power supply winding L2 and at least two monitoring module power supply windings (L31...L3n). The drive module power supply winding L2 supplies power to the isolated drive module through the rectifier module and the A output terminal, and the monitoring module power supply windings supply power to the auxiliary source monitoring module through their respective rectifier modules and output terminals.

9. A vehicle charger, characterized in that: The on-board charger adopts the auxiliary source monitoring circuit according to any one of claims 1 to 8.

10. The vehicle charger according to claim 9, wherein: The high-voltage battery is a vehicle-mounted high-voltage battery.

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